Scheduled and autonomous transmission and acknowledgement

ABSTRACT

Techniques for efficient signaling to and from a plurality of mobile stations are disclosed. In one embodiment, a subset of mobile stations may be allocated a portion of the shared resource with one or more individual access grants, another subset may be allocated a portion of the shared resource with a single common grant, and yet another subset may be allowed to use a portion of the shared resource without any grant. In another embodiment, an acknowledge and continue command is used to extend all or a subset of the previous grants without the need for additional requests and grants, and their associated overhead. In one embodiment, a traffic to pilot ratio (T/P) is used to allocate a portion of the shared resource, allowing a mobile station flexibility in selecting its transmission format based on T/P.

FIELD

[0001] The present invention relates generally to wirelesscommunications, and more specifically to a novel and improved method andapparatus for scheduled and autonomous transmission and acknowledgement.

BACKGROUND

[0002] Wireless communication systems are widely deployed to providevarious types of communication such as voice and data. These systems maybe based on code division multiple access (CDMA), time division multipleaccess (TDMA), or some other multiple access techniques. A CDMA systemprovides certain advantages over other types of systems, includingincreased system capacity.

[0003] A CDMA system may be designed to support one or more CDMAstandards such as (1) the “TIA/EIA-95-B Mobile Station-Base StationCompatibility Standard for Dual-Mode Wideband Spread Spectrum CellularSystem” (the IS-95 standard), (2) the standard offered by a consortiumnamed “3rd Generation Partnership Project” (3GPP) and embodied in a setof documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS25.213, and 3G TS 25.214 (the W-CDMA standard), (3) the standard offeredby a consortium named “3rd Generation Partnership Project 2” (3GPP2) andembodied in “TR-45.5 Physical Layer Standard for cdma2000 SpreadSpectrum Systems” (the IS-2000 standard), and (4) some other standards.

[0004] In the above named standards, the available spectrum is sharedsimultaneously among a number of users, and techniques such as powercontrol and soft handoff are employed to maintain sufficient quality tosupport delay-sensitive services, such as voice. Data services are alsoavailable. More recently, systems have been proposed that enhance thecapacity for data services by using higher order modulation, very fastfeedback of Carrier to Interference ratio (C/I) from the mobile station,very fast scheduling, and scheduling for services that have more relaxeddelay requirements. An example of such a data-only communication systemusing these techniques is the high data rate (HDR) system that conformsto the TIA/EIA/IS-856 standard (the IS-856 standard).

[0005] In contrast to the other above named standards, an IS-856 systemuses the entire spectrum available in each cell to transmit data to asingle user at one time, selected based on link quality. In so doing,the system spends a greater percentage of time sending data at higherrates when the channel is good, and thereby avoids committing resourcesto support transmission at inefficient rates. The net effect is higherdata capacity, higher peak data rates, and higher average throughput.

[0006] Systems can incorporate support for delay-sensitive data, such asvoice channels or data channels supported in the IS-2000 standard, alongwith support for packet data services such as those described in theIS-856 standard. One such system is described in a proposal submitted byLG Electronics, LSI Logic, Lucent Technologies, Nortel Networks,QUALCOMM Incorporated, and Samsung to the 3rd Generation PartnershipProject 2 (3GPP2). The proposal is detailed in documents entitled“Updated Joint Physical Layer Proposal for 1xEV-DV”, submitted to 3GPP2as document number C50-20010611-009, Jun. 11, 2001; “Results of L3NQSSimulation Study”, submitted to 3GPP2 as document numberC50-20010820-011, Aug. 20, 2001; and “System Simulation Results for theL3NQS Framework Proposal for cdma2000 1xEV-DV”, submitted to 3GPP2 asdocument number C50-20010820-012, Aug. 20, 2001. These, and relateddocuments generated subsequently, such as Revision C of the IS-2000standard, including C.S0001.C through C.S0006.C, are hereinafterreferred to as the 1xEV-DV proposal.

[0007] In order to coordinate usage of the forward and reverse link inan efficient manner, a system, such as the 1xEV-DV proposal, forexample, may need various signaling mechanisms for controllingtransmission between one or more base stations and one or more mobilestations. For example, mobile stations may need a mechanism tocoordinate their data transmissions on the reverse link. Mobile stationswill be, in general, scattered throughout a cell's coverage area, andwill need varying amounts of transmission power by the base station forcommunicating signals or commands effectively on the forward link aswell as by the mobile station for transmitting data on the reverse link.A relatively distant, or low geometry, mobile station may require higherpower forward link commands as well as higher power reverse linktransmission than a relatively close, or high geometry, mobile station.In either case, signaling to coordinate access of a shared resource usesa portion of the shared resource, and thus reduces overall capacity.Examples of such signaling include access requests, access grants, andacknowledgements of received data transmissions.

[0008] As is well known in wireless system design, when a channel can betransmitted using less power for the same reliability, the capacity ofthe system may be improved. Furthermore, reducing the amount ofcoordination overhead while keeping a shared resource, such as acommunication link, fully loaded will also improve capacity. There istherefore a need in the art for efficient transmission scheduling andcoordination as well as reducing system loading allocated to suchcoordination.

SUMMARY

[0009] Embodiments disclosed herein address the need for efficientsignaling to and from a plurality of mobile stations. In one embodiment,a subset of mobile stations may be allocated a portion of the sharedresource with one or more individual access grants, another subset maybe allocated a portion of the shared resource with a single commongrant, and yet another subset may be allowed to use a portion of theshared resource without any grant. In another embodiment, an acknowledgeand continue command is used to extend all or a subset of the previousgrants without the need for additional requests and grants, and theirassociated overhead. In one embodiment, a traffic to pilot ratio (T/P)is used to allocate a portion of the shared resource, allowing a mobilestation flexibility in selecting its transmission format based on T/P.Various other aspects are also presented. These aspects have the benefitof providing efficient utilization of the reverse link capacity,accommodating varying requirements such as low-latency, high throughputor differing quality of service, and reducing forward and reverse linkoverhead for providing these benefits, thus avoiding excessiveinterference and increasing capacity.

[0010] The invention provides methods and system elements that implementvarious aspects, embodiments, and features of the invention, asdescribed in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The features, nature, and advantages of the present inventionwill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

[0012]FIG. 1 is a general block diagram of a wireless communicationsystem capable of supporting a number of users;

[0013]FIG. 2 depicts an example mobile station and base stationconfigured in a system adapted for data communication;

[0014]FIG. 3 is a block diagram of a wireless communication device, suchas a mobile station or base station;

[0015]FIG. 4 depicts an exemplary embodiment of data and control signalsfor reverse link data communication;

[0016]FIG. 5 is a timing diagram illustrating autonomous transmission;

[0017]FIG. 6 illustrates an example system including mobile stationscommunicating with a scheduling base station;

[0018]FIG. 7 illustrates system loading in response to grants andautonomous transmission;

[0019]FIG. 8 is a timing diagram showing the operation of a request andgrant, along with autonomous transmission and operation of the F-CACKCH;

[0020]FIG. 9 is a timing diagram illustrating an example operation ofthe ACK-and-Continue command;

[0021]FIG. 10 is a timing diagram illustrating the operation of a commongrant;

[0022]FIG. 11 is a timing diagram illustrating a non-granting basestation participating in decoding a reverse link transmission from andacknowledgement to a mobile station in soft handoff;

[0023]FIG. 12 is a timing diagram illustrating an example embodiment inwhich re-transmission is given priority over a scheduled grant;

[0024]FIG. 13 is a timing diagram illustrating the effect of a missedrequest;

[0025]FIG. 14 is a timing diagram illustrating delay caused by a missedgrant;

[0026]FIG. 15 is a flowchart illustrating a method of scheduling grantsand acknowledging transmissions;

[0027]FIG. 16 is a flowchart illustrating a method of making requests,receiving grants and acknowledgements, and corresponding datatransmission; and

[0028]FIG. 17 is a flowchart illustrating a method of selectingtransmission parameters in response to an available TIP.

DETAILED DESCRIPTION

[0029]FIG. 1 is a diagram of a wireless communication system 100 thatmay be designed to support one or more CDMA standards and/or designs(e.g., the W-CDMA standard, the IS-95 standard, the cdma2000 standard,the HDR specification, the 1xEV-DV proposal). In an alternativeembodiment, system 100 may additionally support any wireless standard ordesign other than a CDMA system. In the exemplary embodiment, system 100is a 1xEV-DV system.

[0030] For simplicity, system 100 is shown to include three basestations 104 in communication with two mobile stations 106. The basestation and its coverage area are often collectively referred to as a“cell”. In IS-95, cdma2000, or 1xEV-DV systems, for example, a cell mayinclude one or more sectors. In the W-CDMA specification, each sector ofa base station and the sector's coverage area is referred to as a cell.As used herein, the term base station can be used interchangeably withthe terms access point or Node B. The term mobile station can be usedinterchangeably with the terms user equipment (UE), subscriber unit,subscriber station, access terminal, remote terminal, or othercorresponding terms known in the art. The term mobile stationencompasses fixed wireless applications.

[0031] Depending on the CDMA system being implemented, each mobilestation 106 may communicate with one (or possibly more) base stations104 on the forward link at any given moment, and may communicate withone or more base stations on the reverse link depending on whether ornot the mobile station is in soft handoff. The forward link (i.e.,downlink) refers to transmission from the base station to the mobilestation, and the reverse link (i.e., uplink) refers to transmission fromthe mobile station to the base station.

[0032] While the various embodiments described herein are directed toproviding reverse-link or forward-link signals for supporting reverselink transmission, and some may be well suited to the nature of reverselink transmission, those skilled in the art will understand that mobilestations as well as base stations can be equipped to transmit data asdescribed herein and the aspects of the present invention apply in thosesituations as well. The word “exemplary” is used exclusively herein tomean “serving as an example, instance, or illustration.” Any embodimentdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other embodiments.

[0033] 1xEV-DV Forward Link Data Transmission and Reverse Link PowerControl

[0034] A system 100, such as the one described in the 1xEV-DV proposal,generally comprises forward link channels of four classes: overheadchannels, dynamically varying IS-95 and IS-2000 channels, a ForwardPacket Data Channel (F-PDCH), and some spare channels. The overheadchannel assignments vary slowly, they may not change for months. Theyare typically changed when there are major network configurationchanges. The dynamically varying IS-95 and IS-2000 channels areallocated on a per call basis or are used for IS-95, or IS-2000 Release0 through B packet services. Typically, the available base station powerremaining after the overhead channels and dynamically varying channelshave been assigned is allocated to the F-PDCH for remaining dataservices. The F-PDCH may be used for data services that are lesssensitive to delay while the IS-2000 channels are used for moredelay-sensitive services.

[0035] The F-PDCH, similar to the traffic channel in the IS-856standard, is used to send data at the highest supportable data rate toone user in each cell at a time. In IS-856, the entire power of the basestation and the entire space of Walsh functions are available whentransmitting data to a mobile station. However, in the proposed 1xEV-DVsystem, some base station power and some of the Walsh functions areallocated to overhead channels and existing IS-95 and cdma2000 services.The data rate that is supportable depends primarily upon the availablepower and Walsh codes after the power and Walsh codes for the overhead,IS-95, and IS-2000 channels have been assigned. The data transmitted onthe F-PDCH is spread using one or more Walsh codes.

[0036] In the 1xEV-DV proposal, the base station generally transmits toone mobile station on the F-PDCH at a time, although many users may beusing packet services in a cell. (It is also possible to transmit to twoor more users, by scheduling transmissions for the two or more users andallocating power and/or Walsh channels to each user appropriately.)Mobile stations are selected for forward link transmission based uponsome scheduling algorithm.

[0037] In a system similar to IS-856 or 1xEV-DV, scheduling is based inpart on channel quality feedback from the mobile stations beingserviced. For example, in IS-856, mobile stations estimate the qualityof the forward link and compute a transmission rate expected to besustainable for the current conditions. The desired rate from eachmobile station is transmitted to the base station. The schedulingalgorithm may, for example, select a mobile station for transmissionthat supports a relatively higher transmission rate in order to makemore efficient use of the shared communication channel. As anotherexample, in a 1xEV-DV system, each mobile station transmits aCarrier-to-Interference (C/I) estimate as the channel quality estimateon the Reverse Channel Quality Indicator Channel or R-CQICH. Thescheduling algorithm is used to determine the mobile station selectedfor transmission, as well as the appropriate rate and transmissionformat in accordance with the channel quality.

[0038] As described above, a wireless communication system 100 maysupport multiple users sharing the communication resourcesimultaneously, such as an IS-95 system, may allocate the entirecommunication resource to one user at time, such as an IS-856 system, ormay apportion the communication resource to allow both types of access.A 1xEV-DV system is an example of a system that divides thecommunication resource between both types of access, and dynamicallyallocates the apportionment according to user demand. Following is abrief background on how the communication resource can be allocated toaccommodate various users in both types of access systems. Power controlis described for simultaneous access by multiple users, such as IS-95type channels. Rate determination and scheduling is discussed fortime-shared access by multiple users, such as an IS-856 system or thedata-only portion of a 1xEV-DV type system (i.e., the F-PDCH).

[0039] Capacity in a system such as an IS-95 CDMA system is determinedin part by interference generated in transmitting signals to and fromvarious users within the system. A feature of a typical CDMA system isto encode and modulate signals for transmission to or from a mobilestation such that the signals are seen as interference by other mobilestations. For example, on the forward link, the quality of the channelbetween a base station and one mobile station is determined in part byother user interference. To maintain a desired performance level ofcommunication with the mobile station, the transmit power dedicated tothat mobile station must be sufficient to overcome the power transmittedto the other mobile stations served by the base station, as well asother disturbances and degradation experienced in that channel. Thus, toincrease capacity, it is desirable to transmit the minimum powerrequired to each mobile station served.

[0040] In a typical CDMA system, when multiple mobile stations aretransmitting to a base station, it is desirable to receive a pluralityof mobile station signals at the base station at a normalized powerlevel. Thus, for example, a reverse link power control system mayregulate the transmit power from each mobile station such that signalsfrom nearby mobile stations do not overpower signals from farther awaymobile stations. As with the forward link, keeping the transmit power ofeach mobile station at the minimum power level required to maintain thedesired performance level allows for capacity to be optimized, inaddition to other benefits of power savings such as increased talk andstandby times, reduced battery requirements, and the like.

[0041] Capacity in a typical CDMA system, such as IS-95, is constrainedby, among other things, other-user interference. Other-user interferencecan be mitigated through use of power control. The overall performanceof the system, including capacity, voice quality, data transmissionrates and throughput, is dependant upon stations transmitting at thelowest power level to sustain the desired level of performance wheneverpossible. To accomplish this, various power control techniques are knownin the art.

[0042] One class of techniques includes closed loop power control. Forexample, closed loop power control may be deployed on the forward link.Such systems may employ an inner and outer power control loop in themobile station. An outer loop determines a target received power levelaccording to a desired received error rate. For example, a target frameerror rate of 1% may be pre-determined as the desired error rate. Theouter loop may update the target received power level at a relativelyslow rate, such as once per frame or block. In response, the inner loopthen sends up or down power control messages to the base station untilreceived power meets the target. These inner loop power control commandsoccur relatively frequently, so as to quickly adapt the transmittedpower to the level necessary to achieve the desired received signal tonoise and interference ratio for efficient communication. As describedabove, keeping the forward link transmit power for each mobile stationat the lowest level reduces other user interference seen at each mobilestation and allows remaining available transmit power to be reserved forother purposes. In a system such as IS-95, the remaining availabletransmit power can be used to support communication with additionalusers. In a system such as 1xEV-DV, the remaining available transmitpower can be used to support additional users, or to increase thethroughput of the data-only portion of the system.

[0043] In a “data-only” system, such as IS-856, or in the “data-only”portion of a system, such as 1xEV-DV, a control loop may be deployed togovern the transmission from the base station to a mobile station in atime-shared manner. For clarity, in the following discussion,transmission to one mobile station at a time may be described. This isto distinguish from a simultaneous access system, an example of which isIS-95, or various channels in a cdma200 or 1xEV-DV system. Two notes arein order at this point.

[0044] First, the term “data-only” or “data channel” may be used todistinguish a channel from IS-95 type voice or data channels (i.e.simultaneous access channels using power control, as described above)for clarity of discussion only. It will be apparent to those of skill inthe art that data-only or data channels described herein can be used totransmit data of any type, including voice (e.g., voice over InternetProtocol, or VoIP). The usefulness of any particular embodiment for aparticular type of data may be determined in part by the throughputrequirements, latency requirements, and the like. Those of skill in theart will readily adapt various embodiments, combining either access typewith parameters selected to provide the desired levels of latency,throughput, quality of service, and the like.

[0045] Second, a data-only portion of a system, such as that describedfor 1xEV-DV, which is described as time-sharing the communicationresource, can be adapted to provide access on the forward link to morethan one user simultaneously. In examples herein where the communicationresource is described as time-shared to provide communication with onemobile station or user during a certain period, those of skill in theart will readily adapt those examples to allow for time-sharedtransmission to or from more than one mobile station or user within thattime period.

[0046] A typical data communication system may include one or morechannels of various types. More specifically, one or more data channelsare commonly deployed. It is also common for one or more controlchannels to be deployed, although in-band control signaling can beincluded on a data channel. For example, in a 1xEV-DV system, a ForwardPacket Data Control Channel (F-PDCCH) and a Forward Packet Data Channel(F-PDCH) are defined for transmission of control and data, respectively,on the forward link.

[0047]FIG. 2 depicts an example mobile station 106 and base station 104configured in a system 100 adapted for data communication. Base station104 and mobile station 106 are shown communicating on a forward and areverse link. Mobile station 106 receives forward link signals inreceiving subsystem 220. A base station 104 communicating the forwarddata and control channels, detailed below, may be referred to herein asthe serving station for the mobile station 106. An example receivingsubsystem is detailed further below with respect to FIG. 3. ACarrier-to-Interference (C/I) estimate is made for the forward linksignal received from the serving base station in the mobile station 106.A C/I measurement is an example of a channel quality metric used as achannel estimate, and alternate channel quality metrics can be deployedin alternate embodiments. The C/I measurement is delivered totransmission subsystem 210 in the base station 104, an example of whichis detailed further below with respect to FIG. 3.

[0048] The transmission subsystem 210 delivers the C/I estimate over thereverse link where it is delivered to the serving base station. Notethat, in a soft handoff situation, well known in the art, the reverselink signals transmitted from a mobile station may be received by one ormore base stations other than the serving base station, referred toherein as non-serving base stations. Receiving subsystem 230, in basestation 104, receives the C/I information from mobile station 106.

[0049] Scheduler 240, in base station 104, is used to determine whetherand how data should be transmitted to one or more mobile stations withinthe serving cell's coverage area. Any type of scheduling algorithm canbe deployed within the scope of the present invention. One example isdisclosed in U.S. patent application Ser. No. 08/798,951, entitled“METHOD AND APPARATUS FOR FORWARD LINK RATE SCHEDULING”, filed Feb. 11,1997, assigned to the assignee of the present invention.

[0050] In an example 1xEV-DV embodiment, a mobile station is selectedfor forward link transmission when the C/I measurement received fromthat mobile station indicates that data can be transmitted at a certainrate. It is advantageous, in terms of system capacity, to select atarget mobile station such that the shared communication resource isalways utilized at its maximum supportable rate. Thus, the typicaltarget mobile station selected may be the one with the greatest reportedC/I. Other factors may also be incorporated in a scheduling decision.For example, minimum quality of service guarantees may have been made tovarious users. It may be that a mobile station, with a relatively lowerreported C/I, is selected for transmission to maintain a minimum datatransfer rate to that user.

[0051] In the example 1xEV-DV system, scheduler 240 determines whichmobile station to transmit to, and also the data rate, modulationformat, and power level for that transmission. In an alternateembodiment, such as an IS-856 system, for example, a supportablerate/modulation format decision can be made at the mobile station, basedon channel quality measured at the mobile station, and the transmitformat can be transmitted to the serving base station in lieu of the C/Imeasurement. Those of skill in the art will recognize myriadcombinations of supportable rates, modulation formats, power levels, andthe like which can be deployed within the scope of the presentinvention. Furthermore, although in various embodiments described hereinthe scheduling tasks are performed in the base station, in alternateembodiments, some or all of the scheduling process may take place in themobile station.

[0052] Scheduler 240 directs transmission subsystem 250 to transmit tothe selected mobile station on the forward link using the selected rate,modulation format, power level, and the like.

[0053] In the example embodiment, messages on the control channel, orF-PDCCH, are transmitted along with data on the data channel, or F-PDCH.The control channel can be used to identify the recipient mobile stationof the data on the F-PDCH, as well as identifying other communicationparameters useful during the communication session. A mobile stationshould receive and demodulate data from the F-PDCH when the F-PDCCHindicates that mobile station is the target of the transmission. Themobile station responds on the reverse link following the receipt ofsuch data with a message indicating the success or failure of thetransmission. Retransmission techniques, well known in the art, arecommonly deployed in data communication systems.

[0054] A mobile station may be in communication with more than one basestation, a condition known as soft handoff. Soft handoff may includemultiple sectors from one base station (or one Base TransceiverSubsystem (BTS)), known as softer handoff, as well as with sectors frommultiple BTSs. Base station sectors in soft handoff are generally storedin a mobile station's Active Set. In a simultaneously sharedcommunication resource system, such as IS-95, IS-2000, or thecorresponding portion of a 1xEV-DV system, the mobile station maycombine forward link signals transmitted from all the sectors in theActive Set. In a data-only system, such as IS-856, or the correspondingportion of a 1xEV-DV system, a mobile station receives a forward linkdata signal from one base station in the Active Set, the serving basestation (determined according to a mobile station selection algorithm,such as those described in the C.S0002.C standard). Other forward linksignals, examples of which are detailed further below, may also bereceived from non-serving base stations.

[0055] Reverse link signals from the mobile station may be received atmultiple base stations, and the quality of the reverse link is generallymaintained for the base stations in the active set. It is possible forreverse link signals received at multiple base stations to be combined.In general, soft combining reverse link signals from non-collocated basestations would require significant network communication bandwidth withvery little delay, and so the example systems listed above do notsupport it. In softer handoff, reverse link signals received at multiplesectors in a single BTS can be combined without network signaling. Whileany type of reverse link signal combining may be deployed within thescope of the present invention, in the example systems described above,reverse link power control maintains quality such that reverse linkframes are successfully decoded at one BTS (switching diversity).

[0056] In a simultaneously shared communication resource system, such asIS-95, IS-2000, or the corresponding portion of a 1xEV-DV system, eachbase station in soft handoff with a mobile station (i.e., in the mobilestation's Active Set) measures the reverse link pilot quality of thatmobile station and sends out a stream of power control commands. InIS-95 or IS-2000 Rev. B, each stream is punctured onto the ForwardFundamental Channel (F-FCH) or the Forward Dedicated Control Channel(F-DCCH), if either is assigned. The stream of commands for a mobilestation is called the Forward Power Control Subchannel (F-PCSCH) forthat mobile station. The mobile station receives the parallel commandstreams from all its Active Set members for each base station (multiplesectors from one BTS, if all in the Active Set of the mobile station,send the same command to that mobile station) and determines if an “up”or “down” command was sent. The mobile station modifies the reverse linktransmit power level accordingly, using the “Or-of-downs” rule, that is,the transmit power level is reduced if any “down” command is received,and increased otherwise.

[0057] The transmit power level of the F-PCSCH is typically tied to thelevel of the host F-FCH or F-DCCH that carries the subchannel. The hostF-FCH or F-DCCH transmit power level at the base station is determinedby the feedback from the mobile station on the Reverse Power ControlSubchannel (R-PCSCH), which occupies the last quarter of the ReversePilot Channel (R-PICH). Since the F-FCH or the F-DCCH from each basestation forms a single stream of traffic channel frames, the R-PCSCHreports the combined decoding results of these legs. Erasures of theF-FCH or the F-DCCH determine the required Eb/Nt set point of the outerloop, which in turn drives the inner loop commands on the R-PCSCH andthus the base station transmit levels of the F-FCH, F-DCCH, as well asthe F-PCSCH on them.

[0058] Due to the potential differences in reverse link path loss toeach base station from a single mobile station in soft handoff, some ofthe base stations in the Active Set may not receive the R-PCSCH reliablyand may not correctly control the forward link power of the F-FCH,F-DCCH, and the F-PCSCH. The base stations may need to re-align thetransmit levels among themselves so that the mobile station retains thespatial diversity gain of soft handoff. Otherwise, some of the forwardlink legs may carry little or no traffic signal energy due to errors inthe feedback from the mobile station.

[0059] Since different base stations may need different mobile stationtransmit power for the same reverse link set point or reception quality,the power control commands from different base stations may be differentand cannot be soft combined at the MS. When new members are added to theActive Set (i.e. no soft handoff to 1-way soft handoff, or from 1-way to2-way, etc.), the F-PCSCH transmit power is increased relative to itshost F-FCH or F-DCCH. This may be because the latter has both morespatial diversity (less total Eb/Nt required) and load sharing (lessenergy per leg) while the former has none.

[0060] By contrast, in a 1xEV-DV system, the Forward Common PowerControl Channel (F-CPCCH) transports the reverse link power controlcommands for mobile stations without the Forward Fundamental Channel(F-FCH) or the Forward Dedicated Control Channel (F-DCCH). In earlierversions of the 1xEV-DV proposal, it has been assumed that the basestation transmit power level of the F-CPCCH is determined by the ReverseChannel Quality Indicator Channel (R-CQICH) received from the mobilestation. The R-CQICH may be used in scheduling, to determine theappropriate forward link transmission format and rate in response toforward link channel quality measurements.

[0061] However, when the mobile station is in soft handoff, the R-CQICHonly reports the forward link pilot quality of the serving base stationsector and therefore cannot be used to directly power control theF-CPCCH from the non-serving base stations. Techniques for this aredisclosed in U.S. Patent Application No. 60/356,929, entitled “Methodand Apparatus for Forward Link Power Control During Soft Handoff in aCommunication System”, filed Feb. 12, 2002, assigned to the assignee ofthe present invention.

[0062] Example Base Station and Mobile Station Embodiments

[0063]FIG. 3 is a block diagram of a wireless communication device, suchas mobile station 106 or base station 104. The blocks depicted in thisexample embodiment will generally be a subset of the components includedin either a base station 104 or mobile station 106. Those of skill inthe art will readily adapt the embodiment shown in FIG. 3 for use in anynumber of base station or mobile station configurations.

[0064] Signals are received at antenna 310 and delivered to receiver320. Receiver 320 performs processing according to one or more wirelesssystem standards, such as the standards listed above. Receiver 320performs various processing such as Radio Frequency (RF) to basebandconversion, amplification, analog to digital conversion, filtering, andthe like. Various techniques for receiving are known in the art.Receiver 320 may be used to measure channel quality of the forward orreverse link, when the device is a mobile station or base station,respectively, although a separate channel quality estimator 335 is shownfor clarity of discussion, detailed below.

[0065] Signals from receiver 320 are demodulated in demodulator 325according to one or more communication standards. In an exampleembodiment, a demodulator capable of demodulating 1xEV-DV signals isdeployed. In alternate embodiments, alternate standards may besupported, and embodiments may support multiple communication formats.Demodulator 330 may perform RAKE receiving, equalization, combining,deinterleaving, decoding, and various other functions as required by theformat of the received signals. Various demodulation techniques areknown in the art. In a base station 104, demodulator 325 will demodulateaccording to the reverse link. In a mobile station 106, demodulator 325will demodulate according to the forward link. Both the data and controlchannels described herein are examples of channels that can be receivedand demodulated in receiver 320 and demodulator 325. Demodulation of theforward data channel will occur in accordance with signaling on thecontrol channel, as described above.

[0066] Message decoder 330 receives demodulated data and extractssignals or messages directed to the mobile station 106 or base station104 on the forward or reverse links, respectively. Message decoder 330decodes various messages used in setting up, maintaining and tearingdown a call (including voice or data sessions) on a system. Messages mayinclude channel quality indications, such as C/I measurements, powercontrol messages, or control channel messages used for demodulating theforward data channel. Various types of control messages may be decodedin either a base station 104 or mobile station 106 as transmitted on thereverse or forward links, respectively. For example, described below arerequest messages and grant messages for scheduling reverse link datatransmission for generation in a mobile station or base station,respectively. Various other message types are known in the art and maybe specified in the various communication standards being supported. Themessages are delivered to processor 350 for use in subsequentprocessing. Some or all of the functions of message decoder 330 may becarried out in processor 350, although a discrete block is shown forclarity of discussion. Alternatively, demodulator 325 may decode certaininformation and send it directly to processor 350 (a single bit messagesuch as an ACK/NAK or a power control up/down command are examples). Anexample command signal, the Forward Common Acknowledgement Channel(F-CACKCH) is used to describe various embodiments below.

[0067] Channel quality estimator 335 is connected to receiver 320, andused for making various power level estimates for use in proceduresdescribed herein, as well as for use in various other processing used incommunication, such as demodulation. In a mobile station 106, C/Imeasurements may be made. In addition, measurements of any signal orchannel used in the system may be measured in the channel qualityestimator 335 of a given embodiment. As described more fully below,power control channels are another example. In a base station 104 ormobile station 106, signal strength estimations, such as received pilotpower can be made. Channel quality estimator 335 is shown as a discreteblock for clarity of discussion only. It is common for such a block tobe incorporated within another block, such as receiver 320 ordemodulator 325. Various types of signal strength estimates can be made,depending on which signal or which system type is being estimated. Ingeneral, any type of channel quality metric estimation block can bedeployed in place of channel quality estimator 335 within the scope ofthe present invention. In a base station 104, the channel qualityestimates are delivered to processor 350 for use in scheduling, ordetermining the reverse link quality, as described further below.Channel quality estimates may be used to determine whether up or downpower control commands are required to drive either the forward orreverse link power to the desired set point. The desired set point maybe determined with an outer loop power control mechanism, as describedabove.

[0068] Signals are transmitted via antenna 310. Transmitted signals areformatted in transmitter 370 according to one or more wireless systemstandards, such as those listed above. Examples of components that maybe included in transmitter 370 are amplifiers, filters,digital-to-analog (D/A) converters, radio frequency (RF) converters, andthe like. Data for transmission is provided to transmitter 370 bymodulator 365. Data and control channels can be formatted fortransmission in accordance with a variety of formats. Data fortransmission on the forward link data channel may be formatted inmodulator 365 according to a rate and modulation format indicated by ascheduling algorithm in accordance with a C/I or other channel qualitymeasurement. A scheduler, such as scheduler 240, described above, mayreside in processor 350. Similarly, transmitter 370 may be directed totransmit at a power level in accordance with the scheduling algorithm.Examples of components which may be incorporated in modulator 365include encoders, interleavers, spreaders, and modulators of varioustypes. A reverse link design, including example modulation formats andaccess control, suitable for deployment on a 1xEV-DV system is alsodescribed below,

[0069] Message generator 360 may be used to prepare messages of varioustypes, as described herein. For example, C/I messages may be generatedin a mobile station for transmission on the reverse link. Various typesof control messages may be generated in either a base station 104 ormobile station 106 for transmission on the forward or reverse links,respectively. For example, described below are request messages andgrant messages for scheduling reverse link data transmission forgeneration in a mobile station or base station, respectively.

[0070] Data received and demodulated in demodulator 325 may be deliveredto processor 350 for use in voice or data communications, as well as tovarious other components. Similarly data for transmission may bedirected to modulator 365 and transmitter 370 from processor 350. Forexample, various data applications may be present on processor 350, oron another processor included in the wireless communication device 104or 106 (not shown). A base station 104 may be connected, via otherequipment not shown, to one or more external networks, such as theInternet (not shown). A mobile station 106 may include a link to anexternal device, such as a laptop computer (not shown).

[0071] Processor 350 may be a general-purpose microprocessor, a digitalsignal processor (DSP), or a special-purpose processor. Processor 350may perform some or all of the functions of receiver 320, demodulator325, message decoder 330, channel quality estimator 335, messagegenerator 360, modulator 365, or transmitter 370, as well as any otherprocessing required by the wireless communication device. Processor 350may be connected with special-purpose hardware to assist in these tasks(details not shown). Data or voice applications may be external, such asan externally connected laptop computer or connection to a network, mayrun on an additional processor within wireless communication device 104or 106 (not shown), or may run on processor 350 itself. Processor 350 isconnected with memory 355, which can be used for storing data as well asinstructions for performing the various procedures and methods describedherein. Those of skill in the art will recognize that memory 355 may becomprised of one or more memory components of various types, that may beembedded in whole or in part within processor 350.

[0072] 1xEV-DV Reverse Link Design Considerations

[0073] In this section, various factors considered in the design of anexample embodiment of a reverse link of a wireless communication systemare described. In many of the embodiments, detailed further in followingsections, signals, parameters, and procedures associated with the1xEV-DV standard are used. This standard is described for illustrativepurposes only, as each of the aspects described herein, and combinationsthereof, may be applied to any number of communication systems withinthe scope of the present invention. This section serves as a partialsummary of various aspects of the invention, although it is notexhaustive. Example embodiments are detailed further in subsequentsections below, in which additional aspects are described.

[0074] In many cases, reverse link capacity is interference limited.Base stations allocate available reverse link communication resources tomobile stations for efficient utilization to maximize throughput inaccordance with Quality of Service (QoS) requirements for the variousmobile stations.

[0075] Maximizing the use of the reverse link communication resourceinvolves several factors. One factor to consider is the mix of scheduledreverse link transmissions from various mobile stations, each of whichmay be experiencing varying channel quality at any given time. Toincrease overall throughput (the aggregate data transmitted by all themobile stations in the cell), it is desirable for the entire reverselink to be fully utilized whenever there is reverse link data to besent. To fill the available capacity, mobile stations may be grantedaccess at the highest rate they can support, and additional mobilestations may be granted access until capacity is reached. One factor abase station may consider in deciding which mobile stations to scheduleis the maximum rate each mobile can support and the amount of data eachmobile station has to send. A mobile station capable of higherthroughput may be selected instead of an alternate mobile station whosechannel does not support the higher throughput.

[0076] Another factor to be considered is the quality of servicerequired by each mobile station. While it may be permissible to delayaccess to one mobile station in hopes that the channel will improve,opting instead to select a better situated mobile station, it may bethat suboptimal mobile stations may need to be granted access to meetminimum quality of service guarantees. Thus, the data throughputscheduled may not be the absolute maximum, but rather maximizedconsidering channel conditions, available mobile station transmit power,and service requirements. It is desirable for any configuration toreduce the signal to noise ratio for the selected mix.

[0077] Various scheduling mechanisms are described below for allowing amobile station to transmit data on the reverse link. One class ofreverse link transmission involves the mobile station making a requestto transmit on the reverse link. The base station makes a determinationof whether resources are available to accommodate the request. A grantcan be made to allow the transmission. This handshake between the mobilestation and the base station introduces a delay before the reverse linkdata can be transmitted. For certain classes of reverse link data, thedelay may be acceptable. Other classes may be more delay-sensitive, andalternate techniques for reverse link transmission are detailed below tomitigate delay.

[0078] In addition, reverse link resources are expended to make arequest for transmission, and forward link resources are expended torespond to the request, i.e. transmit a grant. When a mobile station'schannel quality is low, i.e. low geometry or deep fading, the powerrequired on the forward link to reach the mobile may be relatively high.Various techniques are detailed below to reduce the number or requiredtransmit power of requests and grants required for reverse link datatransmission.

[0079] To avoid the delay introduced by a request/grant handshake, aswell as to conserve the forward and reverse link resources required tosupport them, an autonomous reverse link transmission mode is supported.A mobile station may transmit data at a limited rate on the reverse linkwithout making a request or waiting for a grant.

[0080] The base station allocates a portion of the reverse link capacityto one or more mobile stations. A mobile station that is granted accessis afforded a maximum power level. In the example embodiments describedherein, the reverse link resource is allocated using a Traffic to Pilot(T/P) ratio. Since the pilot signal of each mobile station is adaptivelycontrolled via power control, specifying the T/P ratio indicates theavailable power for use in transmitting data on the reverse link. Thebase station may make specific grants to one or more mobile stations,indicating a T/P value specific to each mobile station. The base stationmay also make a common grant to the remaining mobile stations which haverequested access, indicating a maximum T/P value that is allowed forthose remaining mobile stations to transmit. Autonomous and scheduledtransmission, as well as individual and common grants, are detailedfurther below.

[0081] Various scheduling algorithms are known in the art, and more areyet to be developed, which can be used to determine the various specificand common T/P values for grants in accordance with the number ofregistered mobile stations, the probability of autonomous transmissionby the mobile stations, the number and size of the outstanding requests,expected average response to grants, and any number of other factors. Inone example, a selection is made based on QoS priority, efficiency, andthe achievable throughput from the set of requesting mobile stations.One example scheduling technique is disclosed in co-pending U.S.Provisional Patent Application No. 60/439,989, entitled “SYSTEM ANDMETHOD FOR A TIME-SCALABLE PRIORITY-BASED SCHEDULER”, filed Jan. 13,2003, assigned to the assignee of the present invention. Additionalreferences include U.S. Pat. No. 5,914,950, entitled “METHOD ANDAPPARATUS FOR REVERSE LINK RATE SCHEDULING”, and U.S. Pat. No.5,923,650, also entitled “METHOD AND APPARATUS FOR REVERSE LINK RATESCHEDULING”, both assigned to the assignee of the present invention.

[0082] A mobile station may transmit a packet of data using one or moresubpackets, where each subpacket contains the complete packetinformation (each subpacket is not necessarily encoded identically, asvarious encoding or redundancy may be deployed throughout varioussubpackets). Retransmission techniques may be deployed to ensurereliable transmission, for example ARQ. Thus, if the first subpacket isreceived without error (using a CRC, for example), a positiveAcknowledgement (ACK) is sent to the mobile station and no additionalsubpackets will be sent (recall that each subpacket comprises the entirepacket information, in one form or another). If the first subpacket isnot received correctly, then a Negative Acknowledgement signal (NAK) issent to the mobile station, and the second subpacket will betransmitted. The base station can combine the energy of the twosubpackets and attempt to decode. The process may be repeatedindefinitely, although it is common to specify a maximum number ofsubpackets. In example embodiments described herein, up to foursubpackets may be transmitted. Thus, the probability of correctreception increases as additional subpackets are received. (Note that athird response from a base station, ACK-and-Continue, is useful forreducing request/grant overhead. This option is detailed further below).

[0083] As just described, a mobile station may trade off throughput forlatency in deciding whether to use autonomous transfer to transmit datawith low latency or requesting a higher rate transfer and waiting for acommon or specific grant. In addition, for a given T/P, the mobilestation may select a data rate to suit latency or throughput. Forexample, a mobile station with relatively few bits for transmission maydecide that low latency is desirable. For the available T/P (probablythe autonomous transmission maximum in this example, but could also bethe specific or common grant T/P), the mobile station may select a rateand modulation format such that the probability of the base stationcorrectly receiving the first subpacket is high. Although retransmissionwill be available if necessary, it is likely that this mobile stationwill be able to transmit its data bits in one subpacket. In the exampleembodiments described herein, each subpacket is transmitted in 5 ms.Therefore, in this example, a mobile station may make an immediateautonomous transfer that is likely to be received at the base stationfollowing a 5 ms interval. Note that, alternatively, the mobile stationmay use the availability of additional subpackets to increase the amountof data transmitted for a given T/P. So, a mobile station may selectautonomous transfer to reduce latency associated with requests andgrants, and may additionally trade the throughput for a particular T/Pto minimize the number of subpackets (hence latency) required. Even ifthe full number of subpackets is selected, autonomous transfer will belower latency than request and grant for relatively small datatransfers. Those of skill in the art will recognize that as the amountof data to be transmitted grows, requiring multiple packets fortransmission, the overall latency may be reduced by switching to arequest and grant format, since the penalty of the request and grantwill eventually be offset by the increased throughput of a higher datarate across multiple packets. This process is detailed further below,with an example set of transmission rates and formats that can beassociated with various T/P assignments.

[0084] Mobile stations in varying locations within the cell, andtraveling at varying speeds will experience varying channel conditions.Power control is used to maintain reverse link signals. Pilot powerreceived at base station may be power controlled to be approximatelyequal from various mobile stations. Then, as described above, the T/Pratio is an indicator of the amount of the communication resource usedduring reverse link transmission. It is desirable to maintain the properbalance between pilot and traffic, for a given mobile station transmitpower, transmission rate, and modulation format.

[0085] Mobile stations may have a limited amount of transmit poweravailable. Thus, for example, the communication rate may be limited bythe maximum power of the mobile station power amplifier. Mobile stationtransmit power may also be governed by the base station to avoidexcessive interference with other mobile stations, using power controland various data transmission scheduling techniques. The amount ofavailable mobile station transmit power will be allocated totransmitting one or more pilot channels, one or more data channels, andany other associated control channels. To increase data throughput, therate of transmission may be increased by reducing code rate, increasingthe symbol rate, or using a higher order modulation scheme. To beeffective, the associated pilot channel must be received reliably toprovide a phase reference for demodulation. Thus, a portion of theavailable transmit power is allocated to the pilot, and increasing thatportion will increase the reliability of pilot reception. However,increasing the portion of available transmit power allocated to thepilot also decreases the amount of power available for datatransmission, and increasing the portion of available transmit powerallocated to the data also increases demodulation reliability. Anappropriate modulation format and transmission rate can be determinedfor a given T/P.

[0086] Due to variations in data transmission demand, and discontinuousallocation of the reverse link to mobile stations, the transmission ratefor a mobile station may vary rapidly. The desired pilot power level fora transmission rate and format may thus change instantaneously, as justdescribed. Without prior knowledge of rate changes (which may beexpected in the absence of costly signaling or reduced flexibility inscheduling), a power control loop may attempt to counteract a suddenchange in received power at the base station, perhaps interfering withthe decoding of the beginning of the packet. Similarly, due toincremental step sizes commonly deployed in power control, it may take arelatively long time to reduce the pilot once the transmission rate andformat have been reduced. One technique to combat these, and otherphenomena (detailed further below), is to deploy a secondary pilot inaddition to a primary pilot. The primary pilot can be used for powercontrol and demodulation of all channels, including control channels andlow rate data channels. When additional pilot power is needed for higherlevel modulation or increased data rate, additional pilot power may betransmitted on a secondary pilot. The power of the secondary pilot canbe determined relative to the primary pilot and the incremental pilotpower required for the selected transmission. The base station mayreceive both pilots, combine them, and use them to determine phase andmagnitude information for demodulation of the traffic. Instantaneousincreases or decreases in the secondary pilot do not interfere withpower control.

[0087] Example embodiments, detailed further below, realize the benefitsof a secondary pilot, as just described, by use of an already deployedcommunication channel. Thus, capacity is generally improved, since inpart of the expected range of operation, the information transmitted onthe communication channel requires little or no additional capacity thanrequired to perform the pilot function. As is well known in the art, apilot signal is useful for demodulation because it is a known sequence,and hence the phase and magnitude of the signal may be derived from thepilot sequence for demodulation. However, transmitting pilot withoutcarrying data costs reverse link capacity. Hence, unknown data ismodulated on the “secondary pilot”, and thus the unknown sequence mustbe determined in order to extract information useful for demodulation ofthe traffic signal. In an example embodiment, the Reverse RateIndication Channel (R-RICH) is used to provide the Reverse RateIndicator (RRI), the rate associated with the transmission on the R-SCH.In addition, the R-RICH power is adjusted in accordance with the pilotpower requirements, which can be used at the base station to provide asecondary pilot. That the RRI is one of a known set of values aids indetermining the unknown component of the R-RICH channel. In an alternateembodiment, any channel may be modified to serve as a secondary pilot.This technique is detailed further below.

[0088] Reverse Link Data Transmission

[0089] The reverse link is generally quite different than the forwardlink. Following are several reasons: On the forward link, it takesadditional power to transmit from multiple cells—on the reverse link,receiving from more cells reduces the required amount of transmit power.On the reverse link, there are always multiple antennas receiving themobile station. This can mitigate some of the dramatic fading as oftenoccurs on the forward link.

[0090] When the mobile station is in a boundary area between multiplecells, the forward link Ec/Io will dramatically change due to the fadingof the other cells. On the reverse link, the change in interference isnot as dramatic, since any change is due to a variation in the sum ofthe received power of all mobile stations that are transmitting on thereverse link all of which are all power controlled.

[0091] The mobile station is power limited on the reverse link. Thus,the mobile station may be unable to transmit at a very high rate fromtime to time, depending on channel conditions.

[0092] The mobile station may not be able to receive the forward linkfrom the base station that received the mobile station's reverse linktransmission. As a result, if the mobile station relies upon thetransmission of signaling, for example, an acknowledgement, from asingle base station, then that signalling reliability may be low.

[0093] One goal of a reverse link design is to maintain theRise-over-Thermal (RoT) at the base station relatively constant as longas there is reverse link data to be transmitted. Transmission on thereverse link data channel is handled in two different modes:

[0094] Autonomous Transmission: This case is used for traffic requiringlow delay. The mobile station is allowed to transmit immediately, up toa certain transmission rate, determined by the serving base station(i.e. the base station to which the mobile station directs its ChannelQuality Indicator (CQI). A serving base station is also referred to as ascheduling base station or a granting base station. The maximum allowedtransmission rate for autonomous transmission can be signaled by theserving base station dynamically based on system load, congestion, etc.

[0095] Scheduled Transmission: The mobile station sends an estimate ofits buffer size, available power, and other parameters. The base stationdetermines when the mobile station is allowed to transmit. The goal of ascheduler is to limit the number of simultaneous transmissions, thusreducing the interference between mobile stations. The scheduler mayattempt to have mobile stations in regions between cells transmit atlower rates so as to reduce interference to neighboring cells, and totightly control RoT to protect the voice quality on the R-FCH, the DVfeedback on R-CQICH and the acknowledgments (R-ACKCH), as well as thestability of the system.

[0096] Various embodiments, detailed herein, contain one or morefeatures designed to improve throughput, capacity, and overall systemperformance of the reverse link of a wireless communication system. Forillustrative purposes only, the data portion of a 1xEV-DV system, inparticular, optimization of transmission by various mobile stations onthe Enhanced Reverse Supplemental Channel (R-ESCH), is described.Various forward and reverse link channels used in one or more of theexample embodiments are detailed in this section. These channels aregenerally a subset of the channels used in a communication system.

[0097]FIG. 4 depicts an exemplary embodiment of data and control signalsfor reverse link data communication. A mobile station 106 is showncommunicating over various channels, each channel connected to one ormore base stations 104A-104C. Base station 104A is labeled as thescheduling base station. The other base stations 104B and 104C are partof the Active Set of mobile station 106. There are four types of reverselink signals and two types of forward link signals shown. They aredescribed below.

[0098] R-REQCH

[0099] The Reverse Request Channel (R-REQCH) is used by the mobilestation to request from the scheduling base station a reverse linktransmission of data. In the example embodiment, requests are fortransmission on the R-ESCH (detailed further below). In the exampleembodiment, a request on the R-REQCH includes the T/P ratio the mobilestation can support, variable according to changing channel conditions,and the buffer size (i.e. the amount of data awaiting transmission). Therequest may also specify the Quality of Service (QoS) for the dataawaiting transmission. Note that a mobile station may have a single QoSlevel specified for the mobile station, or, alternately, different QoSlevels for different types of data. Higher layer protocols may indicatethe QoS, or other desired parameters (such as latency or throughputrequirements) for various data services. In an alternative embodiment, aReverse Dedicated Control Channel (R-DCCH), used in conjunction withother reverse link signals, such as the Reverse Fundamental Channel(R-FCH) (used for voice services, for example), may be used to carryaccess requests. In general, access requests may be described ascomprising a logical channel, i.e. a Reverse Schedule Request Channel(R-SRCH), which may be mapped onto any existing physical channel, suchas the R-DCCH. The example embodiment is backward compatible withexisting CDMA systems such as cdma2000, and the R-REQCH is a physicalchannel that can be deployed in the absence of either the R-FCH or theR-DCCH. For clarity, the term R-REQCH is used to describe the accessrequest channel in embodiment descriptions herein, although those ofskill in the art will readily extend the principles to any type ofaccess request system, whether the access request channel is logical orphysical. The R-REQCH may be gated off until a request is needed, thusreducing interference and conserving system capacity.

[0100] In the example embodiment, the R-REQCH has 12 input bits, thatconsist of the following: 4 bits to specify the maximum R-ESCH T/P ratiothat the mobile can support, 4 bits to specify the amount of data in themobile's buffer, and 4 bits to specify the QoS. Those of skill in theart will recognize that any number of bits and various other fields maybe included in alternate embodiments.

[0101] F-GCH

[0102] The Forward Grant Channel (F-GCH) is transmitted from thescheduling base station to the mobile station. The F-GCH may becomprised of multiple channels. In the example embodiment, a commonF-GCH channel is deployed for making common grants, and one or moreindividual F-GCH channels are deployed for making individual grants.Grants are made by the scheduling base station in response to one ormore requests from one or more mobile stations on their respectiveR-REQCHs. Grant channels may be labeled as GCH_(x), where the subscriptx identifies the channel number. A channel number 0 may be used toindicate the common grant channel. If N individual channels aredeployed, the subscript x may range from 1 to N.

[0103] An individual grant may be made to one or more mobile stations,each of which gives permission to the identified mobile station totransmit on the R-ESCH at a specified T/P ratio or below. Making grantson the forward link will naturally introduce overhead that uses someforward link capacity. Various options for mitigating the overheadassociated with grants are detailed herein, and other options will beapparent to those of skill in the art in light of the teachings herein.

[0104] One consideration is that mobile stations will be situated suchthat each experiences varying channel quality. Thus, for example, a highgeometry mobile station with a good forward and reverse link channel mayneed a relatively low power for grant signal, and is likely to be ableto take advantage of a high data rate, and hence is desirable for anindividual grant. A low geometry mobile station, or one experiencingdeeper fading, may require significantly more power to receive anindividual grant reliably. Such a mobile station may not be the bestcandidate for an individual grant. A common grant for this mobilestation, detailed below, may be less costly in forward link overhead.

[0105] In the example embodiment, a number of individual F-GCH channelsare deployed to provide the corresponding number of individual grants ata particular time. The F-GCH channels are code division multiplexed.This facilitates the ability to transmit each grant at the power levelrequired to reach just the specific intended mobile station. In analternative embodiment, a single individual grant channel may bedeployed, with the number of individual grants time multiplexed. To varythe power of each grant on a time multiplexed individual F-GCH mayintroduce additional complexity. Any signaling technique for deliveringcommon or individual grants may be deployed within the scope of thepresent invention.

[0106] In some embodiments, a relatively large number of individualgrant channels (i.e. F-GCHs) are deployed, it may be deployed to allowfor a relatively large number of individual grants at one time. In sucha case, it may be desirable to limit the number of individual grantchannels each mobile station has to monitor. In one example embodiment,various subsets of the total number of individual grant channels aredefined. Each mobile station is assigned a subset of individual grantchannels to monitor. This allows the mobile station to reduce processingcomplexity, and correspondingly reduce power consumption. The tradeoffis in scheduling flexibility, since the scheduling base station may notbe able to arbitrarily assign sets of individual grants (e.g., allindividual grants can not be made to members of a single group, sincethose members, by design, do not monitor one or more of the individualgrant channels). Note that this loss of flexibility does not necessarilyresult in a loss of capacity. For illustration, consider and exampleincluding four individual grant channels. The even numbered mobilestations may be assigned to monitor the first two grant channels, andthe odd numbered mobile stations may be assigned to monitor the lasttwo. In another example, the subsets may overlap, such as the evenmobile stations monitoring the first three grant channels, and the oddmobile stations monitoring the last three grant channels. It is clearthat the scheduling base station cannot arbitrarily assign four mobilestations from any one group (even or odd). These examples areillustrative only. Any number of channels with any configuration ofsubsets may be deployed within the scope of the present invention.

[0107] The remaining mobile stations, having made a request, but notreceiving an individual grant, may be given permission to transmit onthe R-ESCH using a common grant, which specifies a maximum T/P ratiothat each of the remaining mobile stations must adhere to. The commonF-GCH may also be referred to as the Forward Common Grant Channel(F-CGCH). A mobile station monitors the one or more individual grantchannels (or a subset thereof) as well as the common F-GCH. Unless givenan individual grant, the mobile station may transmit if a common grantis issued. The common grant indicates the maximum T/P ratio at which theremaining mobile stations (the common grant mobile stations) maytransmit for the data with certain type of QoS.

[0108] In the example embodiment, each common grant is valid for anumber of subpacket transmission intervals. Once receiving a commongrant, a mobile station which has sent a request but doesn't get anindividual grant may start to transmit one or more encoder packetswithin the subsequent transmission intervals. The grant information maybe repeated multiple times. This allows the common grant to betransmitted at a reduced power level with respect to an individualgrant. Each mobile station may combine the energy from multipletransmissions to reliably decode the common grant. Therefore, a commongrant may be selected for mobile stations with low-geometry, forexample, where an individual grant is deemed too costly in terms offorward link capacity. However, common grants still require overhead,and various techniques for reducing this overhead are detailed below.

[0109] The F-GCH is sent by the base station to each mobile station thatthe base station schedules for transmission of a new R-ESCH packet. Itmay also be sent during a transmission or a retransmission of an encoderpacket to force the mobile station to modify the T/P ratio of itstransmission for the subsequent subpackets of the encoder packet in casecongestion control becomes necessary.

[0110] Detailed below are examples of timing, including variousembodiments with requirements for the interrelationship of accessrequests and grants of either type (individual or common). Additionally,techniques for reducing the number of grants, and thus the associatedoverhead, as well as for congestion control are detailed below.

[0111] In the example embodiment, the common grant consists of 12 bitsincluding a 3-bit type field to specify the format of the next ninebits. The remaining bits indicate the maximum allowed T/P ratio for 3classes of mobiles as specified in the type field, with 3 bits denotingthe maximum allowable T/P ratio for each class. The mobile classes maybe based on grade-of-service (GOS) requirements, or other criterion.Various other common grant formats are envisioned, and will be readilyapparent to one of ordinary skill in the art.

[0112] In the example embodiment, an individual grant comprises 12 bitsincluding: 11 bits to specify the Mobile ID and maximum allowed T/Pratio for the mobile station being granted to transmit, or to explicitlysignal the mobile station to change its maximum allowed T/P ratio,including setting the maximum allowed T/P ratio to 0 (i.e., telling themobile station not to transmit the R-ESCH). The bits specify the MobileID (1 of 192 values) and the maximum allowed T/P (1 of 10 values) forthe specified mobile. In an alternate embodiment, 1 long-grant bit maybe set for the specified mobile. When the long-grant bit is set to one,the mobile station is granted permission to transmit a relatively largefixed, predetermined number (which can be updated with signaling) ofpackets on that ARQ channel. If the long-grant bit is set to zero, themobile station is granted to transmit one packet. A mobile may be toldto turn off its R-ESCH transmissions with the zero T/P ratiospecification, and this may be used to signal the mobile station to turnoff its transmission on the R-ESCH for a single subpacket transmissionof a single packet if the long-grant bit is off or for a longer periodif the long-grant bit is on.

[0113] R-PICH

[0114] The Reverse Pilot Channel (R-PICH) is transmitted from the mobilestation to the base stations in the Active Set. The power in the R-PICHmay be measured at one or more base stations for use in reverse linkpower control. As is well known in the art, pilot signals may be used toprovide amplitude and phase measurements for use in coherentdemodulation. As described above, the amount of transmit power availableto the mobile station (whether limited by the scheduling base station orthe inherent limitations of the mobile station's power amplifier) issplit among the pilot channel, traffic channel or channels, and controlchannels. Additional pilot power may be needed for higher data rates andmodulation formats. To simplify the use of the R-PICH for power control,and to avoid some of the problems associated with instantaneous changesin required pilot power, an additional channel may be allocated for useas a supplemental or secondary pilot. Although, generally, pilot signalsare transmitted using known data sequences, as disclosed herein, aninformation bearing signal may also be deployed for use in generatingreference information for demodulation. In an example embodiment, theR-RICH (detailed below) is used to carry the additional pilot powerdesired.

[0115] R-RICH

[0116] The Reverse Rate Indicator Channel (R-RICH) is used by the mobilestation to indicate the transmission format on the reverse trafficchannel, R-ESCH. The R-RICH comprises 5-bit messages. The orthogonalencoder block maps each 5-bit input sequence into a 32-symbol orthogonalsequence. For example each 5-bit input sequence could be mapped to adifferent Walsh code of length 32. A sequence repetition block repeatsthe sequence of 32 input symbols three times. A bit repetition blockprovides at its output the input bit repeated 96 times. A sequenceselector block selects between the two inputs, and passes that input tothe output. For zero rates, the output of the bit repetition block ispassed through. For all other rates, the output of the sequencerepetition block is passed through. A signal point mapping block maps aninput bit 0 to +1, and an input 1 to −1. Following the signal pointmapping block is a Walsh spreading block. The Walsh spreading blockspreads each input symbol to 64 chips. Each input symbols multiplies aWalsh code W(48, 64). A Walsh code W(48,64) is the Walsh code of length64 chips, and index 48. TIA/EIA IS-2000 provides tables describing Walshcodes of various lengths.

[0117] Those of skill in the art will recognize that this channelstructure is one example only. Various other encoding, repetition,interleaving, signal point mapping, or Walsh encoding parameters couldbe deployed in alternate embodiments. Additional encoding or formattingtechniques, well known in the art, may also be deployed. Thesemodifications fall within the scope of the present invention.

[0118] R-ESCH

[0119] The Enhanced Reverse Supplemental Channel (R-ESCH) is used as thereverse link traffic data channel in the example embodiments describedherein. Any number of transmission rates and modulation formats may bedeployed for the R-ESCH. In an example embodiment, the R-ESCH has thefollowing properties: Physical layer retransmissions are supported. Forretransmissions when the first code is a Rate ¼ code, the retransmissionuses a Rate ¼ code and Chase combining is used. For retransmissions whenthe first code is a rate greater than ¼, incremental redundancy is used.The underlying code is a Rate ⅕ code. Alternatively, incrementalredundancy could also be used for all the cases.

[0120] Hybrid Automatic-Repeat-Request (HARQ) is supported for bothautonomous and scheduled users, both of which may access the R-ESCH.

[0121] For the case in which the first code is a Rate {fraction (1/)}2code, the frame is encoded as a Rate ¼ code and the encoded symbols aredivided equally into two parts. The first half of the symbols are sentin the first transmission, the second half in the second transmission,then the first half in the third transmission and so on.

[0122] Multiple ARQ-channel synchronous operation may be supported withfixed timing between the retransmissions: a fixed number of sub-packetsbetween consecutive sub-packets of same packet may be allowed.Interlaced transmissions are allowed as well. As an example, for 5 msframes, 4 channel ARQ could be supported with 3 subpacket delay betweensubpackets.

[0123] Table 1 lists example data rates for the Enhanced ReverseSupplemental Channel. A 5 ms subpacket size is described, and theaccompanying channels have been designed to suit this choice. Othersubpacket sizes may also be chosen, as will be readily apparent to thoseof skill in the art. The pilot reference level is not adjusted for thesechannels, i.e. the base station has the flexibility of choosing the T/Pto target a given operating point. This max T/P value is signaled on theforward Grant Channel. The mobile station may use a lower T/P if it isrunning out of power to transmit, letting HARQ meet the required QoS.Layer 3 signaling messages may also be transmitted over the R-ESCH,allowing the system to operate without the FCH/DCCH. TABLE 1 EnhancedReverse Supplemental Channel Parameters Number Symbol Effective ofNumber Repetition Number of Code Bits per of Data Factor Binary CodeRate Encoder 5-ms Data Rate Rate/ Code Before the Walsh Symbols in AllIncluding Packet Slots (kbps) 9.6 kbps Rate Interleaver ModulationChannels the Subpackets Repetition 192 4 9.6 1.000 ¼ 2 BPSK on I ++−−6,144 {fraction ( 1/32)} 192 3 12.8 1.333 ¼ 2 BPSK on I ++−− 4,608{fraction ( 1/24)} 192 2 19.2 2.000 ¼ 2 BPSK on I ++−− 3,072 {fraction( 1/16)} 192 1 38.4 4.000 ¼ 2 BPSK on I ++−− 1,536 ⅛ 384 4 19.2 2.000 ¼1 BPSK on I ++−− 6,144 {fraction ( 1/16)} 384 3 25.6 2.667 ¼ 1 BPSK on I++−− 4,608 {fraction ( 1/12)} 384 2 38.4 4.000 ¼ 1 BPSK on I ++−− 3,072⅛ 384 1 76.8 8.000 ¼ 1 BPSK on I ++−− 1,536 ¼ 768 4 76.8 4.000 ¼ 1 QPSK++−− 12,288 {fraction ( 1/16)} 768 3 102.4 5.333 ¼ 1 QPSK ++−− 9,216{fraction ( 1/12)} 768 2 153.6 8.000 ¼ 1 QPSK ++−− 6,144 ⅛ 768 1 307.216.000 ¼ 1 QPSK ++−− 3,072 ¼ 1,536 4 76.8 8.000 ¼ 1 QPSK +− 24,576{fraction ( 1/16)} 1,536 3 102.4 10.667 ¼ 1 QPSK +− 18,432 {fraction( 1/12)} 1,536 2 153.6 16.000 ¼ 1 QPSK +− 12,288 ⅛ 1,536 1 307.2 32.000¼ 1 QPSK +− 6,144 ¼ 2,304 4 115.2 12.000 ¼ 1 QPSK ++−−/+− 36,864{fraction ( 1/16)} 2,304 3 153.6 16.000 ¼ 1 QPSK ++−−/+− 27,648{fraction ( 1/12)} 2,304 2 230.4 24.000 ¼ 1 QPSK ++−−/+− 18,432 ⅛ 2,3041 460.8 48.000 ¼ 1 QPSK ++−−/+− 9,216 ¼ 3,072 4 153.6 16.000 ⅕ 1 QPSK++−−/+− 36,864 {fraction ( 1/12)} 3,072 3 204.8 21.333 ⅕ 1 QPSK ++−−/+−27,648 {fraction (1/9)} 3,072 2 307.2 32.000 ⅕ 1 QPSK ++−−/+− 18,432 ⅙3,072 1 614.4 64.000 ⅕ 1 QPSK ++−−/+− 9,216 ⅓ 4,608 4 230.4 24.000 ⅕ 1QPSK ++−−/+− 36,864 ⅛ 4,608 3 307.2 32.000 ⅕ 1 QPSK ++−−/+− 27,648 ⅙4,608 2 460.8 48.000 ⅕ 1 QPSK ++−−/+− 18,432 ¼ 4,608 1 921.6 96.000 ⅕ 1QPSK ++−−/+− 9,216 ½ 6,144 4 307.2 32.000 ⅕ 1 QPSK ++−−/+− 36,864 ⅙6,144 3 409.6 42.667 ⅕ 1 QPSK ++−−/+− 27,648 {fraction (2/9)} 6,144 2614.4 64.000 ⅕ 1 QPSK ++−−/+− 18,432 ⅓ 6,144 1 1228.8 128.000 ⅕ 1 QPSK++−−/+− 9,216 ⅔

[0124] In an example embodiment, turbo coding is used for all the rates.With R=¼ coding, an interleaver similar to the current cdma2000 reverselink is used, and, if a second subpacket is transmitted, it has the sameformat as the first subpacket. With R=⅕ coding, an interleaver similarto the cdma2000 Forward Packet Data Channel is used, and if a secondsubpacket is transmitted, the sequence of encoded and interleavedsymbols selected for the second subpacket follow those selected for thefirst subpacket. At most, two subpacket transmissions are allowed, andif a second subpacket is transmitted, it uses the same data rate as thefirst subpacket transmission.

[0125] The number of bits per encoder packet includes the CRC bits and 6tail bits. For an encoder packet size of 192 bits, a 12-bit CRC is used;otherwise, a 16-bit CRC is used. The number of information bits perframe is 2 more than with the corresponding rates with cdma2000. The5-ms slots are assumed to be separated by 15 ms to allow time forACK/NAK responses. If an ACK is received, the remaining slots of thepacket are not transmitted.

[0126] The 5 ms subpacket duration, and associated parameters, justdescribed, serve as an example only. Any number of combinations ofrates, formats, subpacket repetition options, subpacket duration, etc.will be readily apparent to those of skill in the art in light of theteaching herein. An alternate 10 ms embodiment, using 3 ARQ channels,could be deployed. In one embodiment, a single subpacket duration orframe size is selected. For example, either a 5 ms or 10 ms structurewould be selected. In an alternate embodiment, a system may supportmultiple frame durations.

[0127] F-CACKCH

[0128] The Forward Common Acknowledgement Channel, or F-CACKCH, is usedby the base station to acknowledge the correct reception of the R-ESCH,as well as to extend an existing grant. An acknowledgement (ACK) on theF-CACKCH indicates correct reception of a subpacket. Additionaltransmission of that subpacket by the mobile station is unnecessary. Thenegative acknowledgement (NAK) on the F-CACKCH allows the mobile stationto transmit the next subpacket up to the maximum allowed number ofsubpacket per packet. A third command, the ACK-and-Continue, allows thebase station to acknowledge successful reception of a packet and, at thesame time, permit the mobile station to transmit using the grant thatled to the successfully received packet. One embodiment of the F-CACKCHuses +1 values for the ACK symbols, NULL symbols for the NAK symbols,and −1 values for the ACK-and-Continue symbols. In various exampleembodiments, detailed further below, up to 96 Mobile IDs can besupported on one F-CACKCH. Additional F-CACKCHs may be deployed tosupport additional Mobile IDs.

[0129] On-off keying (i.e., not sending NAK) on the F-CACKCH allows thebase stations (especially non-scheduling base stations) an option of notsending the ACK when the cost (required power) of doing so is too high.This provides the base station a trade-off between the forward link andreverse link capacity, since a correctly received packet that is notACKed will likely trigger a re-transmission at a later point in time.

[0130] A Hadamard Encoder is one example of an encoder for mapping ontoa set of orthogonal functions. Various other techniques may also bedeployed. For example, any Walsh Code or Orthogonal Variable SpreadingFactor (OVSF) code generation may be used to encode. Different users maybe transmitted to at different power levels if independent gain blocksare deployed. The F-CACKCH conveys one dedicated tri-valued flag peruser. Each user monitors the F-ACKCH from all base stations in itsActive Set (or, alternatively, signaling may define a reduced active setto reduce complexity).

[0131] In various embodiments, two channels are each covered by a128-chip Walsh cover sequence. One channel is transmitted on the Ichannel, and the other is transmitted on the Q channel. Anotherembodiment of the F-CACKCH uses a single 128-chip Walsh cover sequenceto support up to 192 mobile stations simultaneously. This approach uses10-ms duration for each tri-valued flag.

[0132] There are several ways of operating the ACK channel. In oneembodiment, it may be operated such that a “1” is transmitted for anACK. No transmission implies a NAK, or the “off” state. A “−1”transmission refers to ACK-and-Continue, i.e. the same grant is repeatedto the mobile station. This saves the overhead of a new grant channel.

[0133] To review, when the mobile station has a packet to send thatrequires usage of the R-ESCH, it sends the request on the R-REQCH. Thebase station may respond with a grant using the F-CGCH, or an F-GCH.However, this operation is somewhat expensive. To reduce the forwardlink overhead, F-CACKCH can send the “ACK-and-Continue” flag, whichextends the existing grant at low cost by the scheduling base station.This method works for both individual and common grants.ACK-and-Continue is used from the granting base station, and extends thecurrent grant for 1 more encoder packet on the same ARQ channel.

[0134] Note that, as shown in FIG. 4, not every base station in theActive Set is required to send back the F-CACKCH. The set of basestations sending the F-CACKCH in soft handoff may be a subset of theActive Set. Example techniques for transmitting the F-CACKCH aredisclosed in co-pending U.S. patent application Ser. No. 10/611,333,entitled “CODE DIVISION MULTIPLEXING COMMANDS ON A CODE DIVISIONMULITIPLEXED CHANNEL”, filed Jun. 30, 2003, assigned to the assignee ofthe present invention.

[0135] Example Embodiments and Timing Diagrams

[0136] To summarize various features introduced above, mobile stationsare authorized to make autonomous transmissions, which, while perhapslimited in throughput, allow for low delay. In such a case, the mobilestation may transmit without request up to a max R-ESCH T/P ratio,T/P_(Max) _(—) _(auto), which may be set and adjusted by the basestation through signaling.

[0137] Scheduling is determined at one or more scheduling base stations,and allocations of reverse link capacity are made through grantstransmitted on the F-GCH at a relatively high rate. Scheduling may thusbe employed to tightly control the reverse link load and thus protectsvoice quality (R-FCH), DV feedback (R-CQICH) and DV acknowledgement(R-ACKCH).

[0138] An individual grant allows detailed control of a mobile station'stransmission. Mobile stations may be selected based upon geometry andQoS to maximize throughput while maintaining required service levels. Acommon grant allows efficient notification, especially for low geometrymobile stations.

[0139] The F-CACKCH channel may send “ACK-and-Continue” commands, whichextend existing grants at low cost. This works with both individualgrants and common grants.

[0140]FIG. 5 is a timing diagram illustrating autonomous transmission.In this example, a 5 ms sub-packet size is deployed, with 4 ARQchannels. In this example, the mobile station has data arrive fortransmission that may be sufficiently transmitted using the autonomoustransmission. The mobile station does not need to suffer the delayintroduced by a request and subsequent grant. Rather, it may immediatelytransmit in the next ARQ channel. In this example system, a mobilestation will not make a request unless it has an amount of data totransmit that is greater than could be transmitted in an autonomoustransmission. The transmission rate, modulation format, and power levelwill be limited by the maximium Traffic to Pilot Ratio (T/P) allowed forautonomous transmission, given in this example by the parameter T/Pauto. So, the mobile station need not make a request unless it hasavailable transmit power to exceed T/P_(max) _(—) _(auto). A mobilestation may opt to use autonomous transmission while making a request,to get the data transmission started (detailed further below). Themobile station may forego a request, even when the amount of data andavailable transmit power is greater than the minimum for a request, topossibly avoid the request and grant process and its associated delay ifthe system disallows autonomous transmission. In this example, themobile station transmits its data in 3 ARQ channels.

[0141] The data transmitted by the mobile station is identified on theline labeled “MS Tx”. Subsequent to the data arrival, the mobile stationelects to send data on 3 of the 4 available ARQ channels. These three 5ms transmissions are labeled Autonomous TX 1-3. Note that the R-RICH istransmitted along with the pilot, as described above. In general, themobile station's transmissions may be received by a single base station,or multiple base stations in soft handoff. For clarity, in FIG. 5, onlya single base station is shown responding to the mobile stationtransmission. The base station responds by transmitting ACK, NAK, orACK-and-Continue commands to the mobile station on the F-CACKCH. Theresponse to the first transmission, Autonomous TX 1, is sentconcurrently with Autonomous TX 3, with a subpacket gap in between toallow time for the base station to fully receive, demodulate, and decodethe first transmission, and determine whether or not the subpacket wasreceived correctly. As described above, previously transmittedsubpackets may be combined with a current subpacket in the demodulationprocess. In this example, the first transmission is not receivedcorrectly. Therefore, the base station will respond with a NAK. In thisembodiment, an ACK is sent as a +1, a NAK is sent as a 0, and anACK-and-Continue is sent as a −1. So, since a NAK is sent as a 0, a NAKis indicated by not transmitting on the F-CACKCH, as described above.The second and third transmissions are received correctly, and ACKedaccordingly. Note that three ARQ channels are used by this mobilestation, and the fourth is left vacant. In general, a mobile station mayautonomously transmit during any ARQ period.

[0142] In this example, the NAK sent for the first transmission was notfor the final subpacket (in this example, up to four transmissions ofsubpackets are allowed for each packet). So, the mobile station willretransmit. In order to receive and decode the F-CACKCH command, asubpacket delay will occur between the NAK 1 and the retransmission ofthe first transmission, Re-Tx 1. Thus, in this example, there is a 20 msre-transmission delay, as shown.

[0143]FIG. 6 illustrates an example system with mobile stationscommunicating with a scheduling base station. One group of mobilestations, MS_(A)-MS_(N), have no data to transmit. Another group ofmobile stations, MS_(N+1)-MS_(N+M), will transmit autonomously, with norequest. Four mobile stations, MS₁-MS₄, will make a request to thescheduling base station, BS, as well as transmit autonomously whileawaiting a possible grant. These transmissions and requests occur in thecolumn labeled Request.

[0144] A mobile station requests the R-ESCH high rate transmission whenit has enough power and enough data. The supportable R-ESCH T/P is atleast one level higher than T/P_(Max) _(—) _(auto), and, the data in thebuffer is enough to fill at least one encoder packet larger thansupported by T/P_(Max) _(—) _(auto), after accounting for autonomoustransmission and T/P_(Max) _(—) _(auto) during the granting delay. Inthis embodiment, requests may also be limited with a minimum re-requesttime. To avoid excessive requests, a timer may be used to make sure apre-determined amount of time has transpired between a previous requestand a new request while the power and queue conditions just describedare satisfied. Note that the timer length may be set deterministicallyor probabilistically. Various embodiments may allow that a timerrequirement may be overridden when the buffer size has increased orsupportable T/P has changed since the last request as well. In thisembodiment, a mobile station requests R-ESCH transmission using theR-REQCH. An example request message comprises 4 bits each forsupportable R-ESCH T/P, data queue size, and QoS level. Myriad requestmessage configurations are envisioned, and will be readily deployed bythose of skill in the art in light of the teachings herein.

[0145] Various priority schemes may also be deployed. For example, QoSclass may determine whether, or at what rate, the mobile station maysend a request. For example, a premium subscriber may be given higheraccess priority in comparison with an economy subscriber. Differing datatypes may also be assigned differing priorities. A priority scheme maybe deterministic or probabilistic. The parameters associated with thepriority scheme may be updated through signaling, and may be modifiedbased on system conditions such as loading.

[0146] In the column identified as “Grant: Individual and Common”, thescheduling base station, BS, receives the transmissions and requests. BSdetermines how to assign grants based on the requests received. The BSmay take into account the expected number of autonomous transmissionsand the available reverse link capacity (in accordance with othersupported channels, including non-DV channels such as voice and otherreverse link data or control channels) in order to determine what typeof grants, if any, may be supported. In this example, GCH₀ is defined asthe common grant channel. A common grant is issued, including a type,QoS, and T/P for the grant. In this example, a type of “000” isidentified, quality of service QoS₁, and T/P=5 dB are given for thecommon grant. Those of skill in the art will recognize that any numberof types or QoS designations may be deployed in any given system. In analternate embodiment, a common grant may simply apply to any requestingmobile station, any requesting mobile stations with a quality of servicerequirement above some level, or any desired level of complexity may bedeployed to configure various mobile stations to respond to a grant,based on the desired level of differentiation between mobile stations.In another alternate embodiment, multiple common grant channels may bedeployed, with various mobile stations assigned to respond to grants ondiffering subsets of the grant channels. This assignment may be based onthe QoS level the mobile stations need, the soft handoff situation ofthe mobile station, or other factors.

[0147] In this embodiment, the base station may make specific grants, orindividual grants, to up to N mobile stations simultaneously, totransmit one new encoder packet. The number, N, of individual grants maybe determined according to the system capacity, as well as to varyingload conditions.

[0148] In the example shown, one mobile station is granted per F-GCH(except the common grant channel, GCH₀), although, in an alternateembodiment, specific grants could be directed to a group of mobilestations assigned to a grant channel by the use of a common (group) IDthat is assigned to the mobile stations in the group. In this example,the grant message comprises a 12-bit payload, with an 8-bit mobilestation ID and a 4-bit allowed R-ESCH T/P. The individual grant appliesto a single ARQ channel. In an alternate embodiment, a long grantmessage may also be supported, with a flag to include one or moreadditional ARQ channels in the grant. In various embodiments describedherein, a single ARQ channel specific grant will be described forclarity. Those of skill in the art will readily expand the principlesdisclosed to long grants.

[0149] To reduce complexity of decoding grants in a mobile station, amobile station may be notified to monitor just a subset of the grantchannels.

[0150] In this embodiment, the base station may make a common grant tothe remaining requesting MS using F-GCH₀. No mobile station ID is neededas the common GCH is on a fixed Walsh code. As detailed further below, amessage on F-GCH₀ is repeated over 20 ms (4 ARQ channels) to saveforward link power. (Recall that one of the benefits of a common grantis to reach low-geometry mobile stations, to which a specific grantwould be relatively costly). The grant message content is extendible: inthis case, 3 bits are designated for a TYPE field. The TYPE field mayspecify any desired parameters. In this example, it also determines theformat for the QoS designation (i.e. Type=“000” corresponds to a 3-bitT/Pj for QoS class j, j=0, 1, 2). Any other types, known in the art, maybe used to extend this channel.

[0151] In this example, two specific grants are made to mobile stationsMS, and MS₃, as indicated by the MAC_IDs 1 and 3. These grants are madeon grant channels GCH, and GCH₂. The two specific grants allow for a T/Pof 8 dB and 12 dB, respectively. The mobile stations given specificgrants will be able to determine the data rate and modulation formatdesired for each assigned T/P (detailed further below). Note that onlyMS, and MS₃ receive specific grants. Thus, MS₂ and MS₄ will rely on thecommon grant, and its lower T/P of 5 dB.

[0152] In the column labeled Transmission, the various mobile stationswill transmit data, if any, according to the common and specific grants,or autonomously, as applicable.

[0153]FIG. 7 illustrates the system loading in response to the grantsand autonomous transmission given in the example of FIG. 6. A targetload is defined for the desired overall system load. An interferencecomponent is identified, which may include the various alternate voiceand/or data channels supported by the system (e.g. non-DV channels in a1xEV-DV system). The common and specific grants are determined to allowthe sum of the granted transmissions (common and individual), expectedautonomous transmission, and interference to be at or below the targetload. Data throughput may be lowered, reducing capacity, if the targetload is exceeded (requiring excessive retransmission). When the systemload is below the target load, some of the reverse link capacity isunutilized. Thus, the scheduling base station determines individualgrants to efficiently load the reverse link. Corresponding to theexample requests depicted in FIG. 6, transmission by mobile stationsMS₁-MS₄ are shown. The base station has flexibility in scheduling. Forexample, in this case, the base station knows from its request that MS₂will complete its transmission within two packets based on the commongrant. Thus, the individual grant to MS, may be increased for the lattertwo packets shown.

[0154]FIG. 8 is a timing diagram showing the operation of a request andgrant, along with autonomous transmission and operation of the F-CACKCH.This example shows a mobile station communicating with a scheduling basestation, without soft handoff. In this example, four 5 ms ARQ channelsare deployed. Myriad other configurations may be deployed by one ofskill in the art in light of the principles disclosed herein.

[0155] Subsequent to data arriving at the mobile station fortransmission, the mobile station determines that the conditions supporta request for a grant of increased throughput on the reverse link. Themobile station forms a request message and transmits it along with anautonomous transmission, TX 1, to get started. The request is 5 ms induration, in this example. A shorter request and/or grant may facilitatefaster assignment of reverse link resources, as well as fasteradjustment of those assignments. A longer request and/or grant can betransmitted at lower power, or can more easily reach lower geometrymobile stations. Any of the various permutations of packet duration,request duration, grant duration, and the like, are envisioned, and willbe readily deployed by those of skill in the art in light of theteaching herein.

[0156] During the following ARQ channel, the base station receives therequest, along with any requests from other supported mobile stations,and decodes them. Subsequent to decoding, the base station makes ascheduling decision, i.e. what types of individual or common grants, ifany, will be made. During this time, the mobile station transmits asecond subpacket, TX 2, autonomously on the second ARQ channel. Themobile station also uses this packet duration to decode the received TX1.

[0157] During the third ARQ channel, a 5 ms grant is made by thescheduling base station to the mobile station. An example grant messageis described above. In addition to identifying the mobile station towhich the grant is made (which may be done in any of a variety of ways,including using a mobile ID, or a specific grant channel for the mobilestation, etc.), a maximum T/P is assigned for the duration of the grant.At the same time, the mobile station continues its autonomoustransmission, transmitting TX 3. The base station has had time to decodeTX 1 and determine if it was received correctly. In this example, itwas, so an ACK is sent on the scheduling (or granting) base station'sF-CACKCH, on a subchannel assigned for this mobile station. Those ofskill in the art will recognize that any alternative technique or meansmay also be deployed to convey the ACK to the sending mobile station.

[0158] During the fourth ARQ channel, the mobile station will bereceiving and decoding the ACK and the Grant from the scheduling basestation. Meanwhile, it continues its autonomous transmission,transmitting TX 4. In this example, the scheduling base station did notreceive the autonomous transmission of TX 2 correctly, thus a NAK of TX2 is indicated by a non-transmission on the F-CACKCH.

[0159] Having decoded the NAK as well as the grant in the fourth ARQchannel, the mobile station makes a scheduled transmission in the fifthpacket, which is again the first ARQ channel. Note that to reduce theforward link overhead, an alternative embodiment does not send an ACK atthe same time an individual GCH is sending a grant to the mobilestation. That is, the mobile station will interpret the reception of agrant as the simultaneous grant and an ACK. Rather than transmitting atthe limited autonomous T/P, the mobile station makes a determination ofthe rate and modulation format desired for the granted T/P, and makesthat transmission, TX 5. Note that, in this example, the R-RICH istransmitted with the rate indicator at increased power, to aid in thedemodulation of the higher rate transmission, as described above. Notethe causal relationship between the request in the first subpacketduration, the grant in response in the third subpacket duration, and thetransmission according to the grant in the fifth. Also during this fifthsubpacket duration, the base station sends an ACK corresponding to TX 3.

[0160] In the sixth subpacket duration, or ARQ 2, the mobile station hasdecoded the NAK of TX 2, and retransmits that subpacket. Meanwhile, thebase station sends an ACK in response to the correct decoding ofautonomous TX 4, and will be attempting to decode the TX 5 transmittedand received in the previous frame.

[0161] In the seventh subpacket duration, the base station hasdetermined that TX 5 was incorrectly decoded, and a NAK is indicated,i.e. not sent, in this example. This may be due to the fact that mobilestation has some discretion over the type of data transmission itdesires, within the T/P parameters specified by the grant. Thus, if lowlatency throughput is desired, the mobile station will select a rate andmodulation format that is likely to result in the first subpacket beingdecoded correctly (although one or more subpackets may still be requiredin this case, the rate may be selected in accordance with the desiredprobability of successful first transmission). Perhaps, in this example,the mobile station has instead opted to select a rate and format to getthe maximum data through during the grant. In such a case, it may belikely that all the subpackets allowed (4, in this example) will berequired before correct decoding takes place. Thus, the next tworetransmissions of packet 5 will also likely be NAKed. The base stationcombines the subpackets from each subsequent transmission to increasethe demodulation performance, as described above. Of course, the ratemay also be selected such that only two re-transmissions are likely tobe required, etc. This selection process will be described in moredetail below. Meanwhile, the mobile station is autonomously transmittingTX 6 on this ARQ channel (ARQ channel 3, in this example).

[0162] During the eighth subpacket duration, the mobile station is givenan opportunity to decode the NAK sent and received in the previousframe. Meanwhile, autonomous transmission continues on this fourth ARQchannel, as TX 7 is transmitted.

[0163] In the ninth subpacket duration, the mobile station has decodedthe NAK of TX 5, and so TX 5 is retransmitted. Note that, in thisexample, there is a 20 ms delay from one transmission to aretransmission of that packet in a subsequent frame. Note also thatthere is a 20 ms delay from the request until the first opportunity, ifany, to transmit in response to the grant made according to the request.

[0164]FIG. 9 is a timing diagram illustrating an example operation ofthe ACK-and-Continue command. This diagram is very similar to FIG. 8, soonly the differences will be highlighted. The same four 5 ms ARQchannels are deployed, and the autonomous transmissions occuridentically as in FIG. 8. TX 2 is NAKed as well, as before.

[0165] In this example, however, note that the individual grant made inresponse to the request is for one encoder packet only. When TX 5 istransmitted in response to the grant, the base station has twoalternatives when TX 5 is received correctly (in FIG. 8 is was receivedin error, and had to be retransmitted). The base station will knowwhether the mobile station's buffer contains more data, as given in therequest. In order to avoid the overhead and cost of signaling associatedwith a new grant and request, the base station may determine that theindividual grant should be continued. Of course, the base station takesinto consideration the expected autonomous loading, the interferencefrom other channels, as well as the other common and individual grants.In this example, the base station makes such a determination, and sendsthe ACK-and-Continue on the F-CACKCH. This indicates to the mobilestation that TX 5 was received correctly, no additional retransmissionswill be necessary. In addition, the mobile station knows that it maycontinue its scheduled transmission without an additional request.Therefore, as shown, in response to the ACK-and-Continue command, themobile station transmits scheduled transmission TX 8.

[0166] If the base station had, for whatever reason, decided that itwould be better for the mobile station not to continue transmitting, anACK could have been sent instead of the Ack-and-Continue. Then, themobile station would still be made aware that TX 5 was receivedcorrectly and that no retransmission will be necessary. However, themobile station's grant has now expired, and so only autonomoustransmission would be available during the ninth subpacket duration(details not shown). Various options and techniques employing the ACKsand ACK-and-Continues will be detailed further below.

[0167]FIG. 10 is a timing diagram illustrating the operation of a commongrant. As described above, all requesting mobile stations may be grantedby a common grant of a maximum R-ESCH T/P, T/P_(Max) _(—) _(Common),where, T/P_(Max) _(—) _(common)>T/P_(Max) _(—) _(auto). A mobile stationwithout an individual grant may use the first F-GCH₀ common grantreceived at a time D_(req) _(—) _(grant) after the request. This delayensures the scheduling base station time to receive the request and tomodify the common grant accordingly. The common grant is valid for therepetition duration of F-GCH₀, starting 5 ms after the end of the grant.These specific parameters are defined for clarity of discussion only, asany parameters may be deployed in alternate embodiments.

[0168] As described in FIG. 9, the base station may use ACK-and-Continueto extend the grant for a commonly granted mobile station. This, ineffect, transfers the selected mobile station's common grant to anindividual grant for each, using the previous common grant to set thetransmission parameters. In addition, sending a new common grant may beused to reduce the T/P for those mobile stations not receiving theACK-and-Continue. The base station is free to refrain from sending a newcommon grant, thus removing all but the selected mobile stations.Sending an ACK to selected mobile stations may be used for removing thecommon grant for those mobile stations. Of course, a specific grant toone or more previously common granted mobile stations may be made toreduce or retract their common grant, although the cost of a specificgrant for this purpose may prove to be too high. In an alternateembodiment, if so desired, a new T/P_(max) _(—) _(common) may apply tocommon granted mobile stations operating with an ACK-and-Continue,allowing their grants to be modified in bulk with a single common grant.In yet another alternative, if the common grant T/P increases from thatused by a mobile station continuing under a common grant withACK-and-Continue, that mobile station may take advantage of the higherT/P. Any combination of these techniques may be deployed. Signaling maybe used to modify the behavior of mobile stations responding to commongrants, and different classes of mobile stations may follow differentrules based on their class. Thus, for example, premium or economy statusmay be given to a mobile station, or to different classifications ofdata type.

[0169] Thus, in this example, the request shown in FIG. 10 is too lateto allow MS, to use Common Grant 1, as shown. A possible request,subsequent to the request shown, would be too late to allow MS₁ to useCommon Grant 2. Note that, in this example, none of the individualgrants transmitted on GCH₂ and GCH₁ are directed to MS₁. In this commongrant example, the common grant is transmitted on GCH₀ and is repeatedover 20 ms. This allows the common grant to be transmitted at arelatively lower power than an individual grant, reducing the reverselink capacity required for the common grant, and allowing it to be usedto reach lower geometry mobile stations. Any encoding scheme may beemployed to increase the effective reach of the common grant. Forexample, the grant may be repeated 4 times, 5 ms for each repetition.The mobile stations may combine as many grant repetitions as required todecode the grant. In another alternative, a Forward Error Control (FEC)encoding scheme may be employed that spreads the grant over the entirecommon grant period. Various encoding schemes are well known in the art.

[0170] The scheduled transmissions of MS, are transmitted in response toCommon Grant 2, with one 5 ms frame in between the end of Common Grant 2and the beginning of the scheduled transmissions, to allow the mobilestation time to decode the common grant. The common grant is valid for20 ms, or 4 ARQ channels. While a grant duration of any length may bedeployed, in this embodiment, a common grant duration that is longerthan the individual grant is used. This allows the frequency of commongrants (which may be used when individual grants are expensive) to belower for a given amount of data transmission. An alternative embodimenthas common grant channels that might have shorter or longer duration butinstead less payload (fewer bits per grant) in order to reduce theforward link power cost. Note that the Walsh space overhead on theforward link by a grant channel with fewer bits is also lowered.

[0171] The delay from the request to the scheduled transmission, CommonGrant Delay, is thus a minimum of 35 ms, which may be longer if therequest had occurred earlier with respect to the beginning of CommonGrant 2. This example allows the base station to take a conservativeapproach to scheduling, in that all the requests are known in advance ofa common grant issue. In a relatively more liberal alternative, a mobilestation may be allowed to tack onto the latest validly received commongrant, requiring the base station to reduce the common grant if thenumber of requests availing of a common grant should prove too high.

[0172] Note that autonomous transmissions are omitted in FIG. 10, forclarity. It may be likely that MS, would send as many autonomoustransmissions as are available during the Common Grant Delay. A systemembodiment may dictate that MS, take advantage of available autonomoustransmission, but this is not mandatory. In various alternateembodiments, a mobile station may be allowed to make the choice to makea request concurrently with autonomous transmission, may be required toautonomously transmit while requesting and waiting for a grant, or maybe prohibited from autonomously transmitting while a request is pending.Those of skill in the art will readily deploy myriad configurations ofautonomous and scheduled transmission, using various combinations ofindividual and common grants.

[0173]FIG. 11 is a timing diagram illustrating a non-granting basestation participating in decoding a reverse link transmission from andacknowledgement to a mobile station in soft handoff. The first sixframes are similar to those depicted in FIG. 8. The mobile station makesa request to transmit data, as well as autonomous transmissions TX 1-4.The granting base station receives the request, decodes it, anddetermines the appropriate scheduling. An individual grant is made,after which the mobile station transmits scheduled transmission TX 5. Asin FIG. 8, the granting base station does not decode TX 2 correctly, andNAKs that subpacket. The non-granting base station, monitoring thereverse link transmissions of the mobile station in soft handoff, doesnot decode correctly any of the first 4 autonomous transmissions TX 1-4.Thus, neither base station ACKs TX 2, and the mobile station retransmitsTX 2, as in FIG. 8. The granting base station also NAKs the scheduledtransmission TX 5, as in FIG. 8. However, the non-granting base stationdoes decode TX 5 correctly, and so an ACK is transmitted on thenon-granting base station's F-CACKCH. Therefore, the re-transmission ofTX 5, shown in FIG. 8, is omitted in the example of FIG. 11 (asindicated by the dashed outline of the retransmission, circled). This isone example of soft handoff base station participation.

[0174] Depending on the coordination of base stations, variousembodiments with differing resulting mobile station behavior may bedeployed. In an example system without tight coordination between basestations, grants as well as ACK-and-Continue commands come from thegranting base station only. In this case, the granting base station mayhave allocated some capacity for the expected retransmission. One optionis to have the mobile station transmit new data in the slot allocatedfor the re-transmission, to utilize the allocated capacity. However, anew grant, or an ACK-and-Continue, in various embodiments, allows themobile station to transmit a pre-determined number of subpackets (4 inthis example). So, if the mobile station's new data requires additionalsubpackets beyond the remainder of those allocated for TX 5, the grantwill have been extended. One solution is for the base station torecognize the new data and factor the possible extension into futurescheduling. An alternative is to restrict the mobile station toselecting a rate and format for the new data transmission that isexpected to terminate within the remaining subpackets allocated in theprevious grant (or ACK-and-Continue). The granting base station may thenACK the new data to stop any additional continuation, if desired. Themobile station may also abort the new data at the end of the previousgrant if it has not been acknowledged (i.e., the mobile station limitsitself to a smaller number of available subpackets for the new datatransmission).

[0175] In an example system in which base stations in soft handoff aremore tightly coordinated, the non-granting base station may be empoweredto send an ACK-and-Continue. The base stations may then coordinate theallocation of system load as appropriate.

[0176] In the example embodiment, while ACK and NAK may be sent frommultiple base stations in soft handoff, ACK-and-Continue comes from thescheduling base station sectors only. Therefore inter-base stationscheduling is not required, which may be a benefit for base stationvendors and system operators. One advantage may be that a very highspeed link between base stations may not be required. For example, ahigh speed backhaul link between multiple base stations would be neededto support data arriving in one 5 ms frame, with 5 ms to decode,followed by transmission of a coordinated ACK, NAK, or ACK-and-Continue.Thus, in one embodiment, a mobile station listens to the serving orscheduling base station only for grants and/or ACK-and-Continue. In analternate embodiment, still with uncoordinated base station grants, themobile station may listen to multiple base stations in soft handoff forgrants and/or ACK-and-Continue, and some arbitration scheme may beemployed when conflicting signals arrive. For example, so as not toexceed the anticipated system load by any granting base station, themobile station may transmit at the minimum allowed grant T/P among allbase stations in the mobile station's Active Set. Note that other mobilestation rules than “minimum of all” can be used, including probabilisticbehavior based on the allowed grant T/P. Conflicting responses includingan ACK-and-Continue may be handled as described above with respect toFIG. 11.

[0177] In an alternate embodiment, with a faster backhaul between basestations, coordination between base stations to transmit to a singlemobile station may be done. So for example, the same command transmittedfrom all base stations may be coordinated and sent (i.e. either type ofgrant, or ACK-and-Continue.)

[0178]FIG. 12 is a timing diagram illustrating an example embodiment inwhich re-transmission is given priority over a scheduled grant. Themobile station makes a request while autonomously transmitting TX 1. Thegranting base station decodes the request and makes a schedulingdecision that will include a grant of the mobile station's request.However, TX 1 is not decoded correctly at the base station, and so TX 1is NAKed. Since the ARQ channel that would be allocated for thescheduled transmission is also the ARQ channel on which TX 1 would bere-transmitted, the base station delays the grant. The reverse linkallocation for that ARQ channel can be assigned to a different mobilestation. In this example, the grant is issued on the following frame.Thus, the mobile station re-transmits TX 1 on the fifth frame, andtransmits the scheduled TX 5 on the subsequent ARQ channel. In this way,the base station may allocate grants to avoid conflicts withre-transmissions. In one embodiment, to take advantage of a higherreliability grant channel, a mobile station may give priority to areceived grant with respect to any NAK, ACK, or ACK-and-Continue commandfrom a lower reliability channel (F-CACKCH).

[0179]FIG. 13 is a timing diagram illustrating the effect of a missedrequest. As before, the mobile station makes a request after dataarrives for transmission. The mobile station would expect the soonestgrant in response, if any, to arrive at a time D_(reg) _(—) _(grant)after the request. This would correspond to the frame in which TX 3 istransmitted, as shown. However, the request is not received at the basestation for some reason, as indicated by the decode failure. Therefore,no grant is made, as indicated by the dashed outline on the grantingbase station F-GCH. If a grant had been made, the mobile station wouldhave used the fourth frame to decode it. In this case, no grant is made,so no grant is decoded. Therefore, it is at the beginning of the fifthframe that the mobile station would first be ready to initiate a newrequest. Thus, four frames from the beginning of the first request wouldbe the minimum delay for a re-request following a missed request. Notethat, accordingly, during the three frames following the request, norequest is made, as indicated by the dashed outlines.

[0180] The first available frame for re-request is illustrated with adashed outline labeled “Possible Re-request”. However, in thisembodiment, the mobile station is equipped to wait an additionalre-request delay, as indicated, before transmitting a new request. Thedelay in this example is two frames. The re-request delay may be used bythe base station to reduce the reverse link load created by the repeatedrequests or to provide QoS differentiation by letting certain classes ofmobile stations re-request faster than others. The re-request delay maybe signaled to mobile stations. It may be deterministic orprobabilistic, i.e., it can be randomized. For example, the mobilestation generates a random number each re-request and determines there-request accordingly. QoS differentiation may be included by biasingthe random numbers appropriately to give premium class mobile stationsor data types a higher probability of lower re-request delay thaneconomy class mobile stations or data types.

[0181] The mobile station, in FIG. 13, sends the re-request as indicatedin frame 7, and the granting base station receives and decodes there-request correctly during frame 8. In response, a grant is issued inthe ninth frame. Note that, since the request was missed, there are nogrants issued on the F-GCH until frame 9.

[0182] Although the example of a missed request is illustrated in FIG.13, the behavior of the mobile station depicted is identical to thesituation in which a mobile station refrains from making any grant,individual or common, to the mobile station. The mobile station does notdifferentiate between a possible missed grant and a denied grant. There-request mechanism is deployed to govern the mobile station'sre-request.

[0183] Note also the impact of a missed request on the granting basestation's scheduling. When a request is not received correctly at agranting base station, any subsequent common grant issued by that basestation will also grant the mobile station whose request was not decodedcorrectly. Thus, that mobile station will transmit and use up a portionof the shared resource that was not factored into the base station'sallocation. There are several ways to handle this issue. First, thegranting base station may simply factor the possible additional mobilestation into the next allocation, modifying the T/P of the common grantto accommodate the extra transmission, if necessary. Anotheralternative, although perhaps prohibitively costly, is for the basestation to signal that mobile station with an individual grantindicating an alternate T/P, or with a special flag indicating themobile station's grant is terminated. However, using an ACK is a moreefficient and effective way to remove a grant that was made in error, oris no longer desired. The base station may simply ACK-and-Continue thosemobile stations for whom the common grant is desired to remaineffective, and ACK those for whom the common grant is to be terminated.

[0184]FIG. 14 is a timing diagram illustrating delay caused by a missedgrant. In the first frame shown, the mobile station has already issued arequest and is transmitting autonomously TX 1. The scheduling basestation issues a grant for the mobile station during that same frame.However, the grant is not received correctly, and so, in the followingframe, the mobile station does not decode the grant. In the third frame,the mobile station re-requests. At the same time, autonomoustransmission TX 3 is sent by the mobile station. However, if the granthad not been missed, it would be in frame 3 that the mobile stationcould have transmitted a scheduled transmission. Instead, the schedulingbase station grants the new request in the fifth frame, which the mobilestation receives and decodes correctly in the sixth frame. The mobilestation makes a scheduled transmission, TX 7, in the seventh frame. Notethe four-frame delay in the scheduled transmission due to the missedgrant.

[0185] In an example embodiment, the scheduling base station may detectthe grant loss when it receives a transmission limited to the autonomousT/P in frame 3. The base station may determine the grant was lost, orthe mobile station was otherwise power limited, in contrast to theexpected T/P allowed in the missed grant. While it is possible that amobile station, having received an individual grant with a higher T/P,would transmit at the lower autonomous T/P limit, it may be unlikely,and the base station could take advantage of the detected likely missedgrant. In the example shown in FIG. 14, the re-request was made withouta re-request delay. Thus, the next frame in the granted ARQ channel,frame 7, will be used for a scheduled transmission, as desired. In analternate example, not shown, if the mobile station was subject to are-request delay, the re-request would not have been received by thescheduling base station in frame 4. The scheduling base station wouldthen be able to reallocate the T/P assigned to the mobile station forframe 7 to another mobile station, so that the system resources wouldnot be underutilized.

[0186]FIG. 15 is a flowchart illustrating a method 1500 of schedulingand acknowledging transmissions. In an example embodiment, this methodmay be iterated indefinitely, repeating the process once for eachsubpacket frame (5 ms, for example). The process starts in step 1510,where the scheduling base station receives access requests from one ormore mobile stations. Note that the scheduling base station may beserving a plurality of mobile stations. A subset of those mobilestations may not have any data to transmit. Another subset may transmitautonomously only. Another subset may send a request for access (alongwith an autonomous data transmission, if applicable).

[0187] In step 1520, the scheduling base station allocates the sharedresource to the expected number of autonomous transmissions, one or moreindividual grants, if any, a common grant for the remainder of therequests, if desired, and any grants that will be extended from previousgrants (individual or common). Some mobile stations may not betransmitting at all, and techniques for estimating the number oftransmitting base stations are known in the art, including using systemstatistics, previous transmissions, the type of data previouslytransmitted, and any number of other factors. A suitable margin to allowfor the uncertainty may be included, which may be pre-determined, ordynamically updated as conditions change. The rest of the mobilestations desiring to transmit will be known, with some exceptions, dueto the access requests, which may also indicate the amount of data totransmit. The base station may keep track of how much data is left totransmit from each of the requesting mobile stations. One exception maybe missed requests, of which the base station will be unaware. Asdescribed above, in such a case, the mobile station whose request ismissed may yet transmit according to a common grant, if one is issued.The base station may include some margin to allow for such unexpectedtransmissions. The base station may also abort unexpected transmissionsquickly using the ACK command instead of the ACK-and-Continue command.Based on the expected autonomous transmission, and any applicablemargins, the base station may allocate the shared resource to the sharedand common grants, if any. Again, mobile stations may be selected forincreased transmission based on their geometry, with QoS factored in, toincrease throughput for a given system load, while maintaining servicelevels. In the example 1xEV-DV system, the shared resource is thebalance of the reverse link not assigned to other channels, as describedabove. The amount of reverse link capacity for allocation to the R-ESCHmay thus vary with time.

[0188] In step 1530, the base station transmits the grants. Individualgrants may be transmitted on one or more individual grant channels.Mobile stations may be assigned to monitor a grant channel specific tothe mobile station, or one or more individual grant channels on which aplurality of mobile stations may be individually granted. In oneembodiment, a single common grant channel is used to transmit a commongrant. In an alternate embodiment, multiple common grants may beallocated, and transmitted on multiple common grant channels. Mobilestations may be assigned to monitor one or more common grant channels,and the number monitored may be a subset of the total number of commongrant channels.

[0189] In step 1540, the base station receives data transmissions fromthe mobile stations. These transmissions will include autonomoustransmissions, as well as any transmissions made in response to anyindividual or common grants. The base station may receive unexpectedtransmissions. For example, a missed request may result in a mobilestation transmitting in response to a common grant. As another example,a mobile station may incorrectly decode an individual grant directed toanother mobile station, and transmit according to that individual grantinstead of a common grant, or instead of refraining from transmission inthe case where no common grant is issued. In yet another example, amobile station may incorrectly decode an ACK or NAK as anACK-and-Continue, thus erroneously extending a previous grant orterminating an unfinished transmission and extending a previous grant.The base station decodes each of the received transmissions anddetermines whether or not the transmissions were decoded in error.

[0190] In step 1550, the base station selectively extends previousgrants, if the allocation allows, to any number of the previouslygranted mobile stations. The base station uses the ACK-and-Continuecommand, thus avoiding the overhead associated with additional requestsand grants. Those transmissions received in error will be NAKed, andretransmission will follow if the maximum number of retransmissions (orsubpackets) has not been reached. Those mobile stations for which agrant is not to be extended (and whose transmissions were decodedwithout a detected error) will be transmitted an ACK. The process thenstops (and may be repeated for the next frame).

[0191]FIG. 16 is a flowchart illustrating a method 1600 of makingrequests, receiving grants and acknowledgements, and corresponding datatransmission. This method is suitable for deployment in a mobile stationcommunicating with a scheduling base station. That base station may beusing a method such as method 1500, described above. This process may beiterated for each frame, in similar fashion as method 1500.

[0192] The process starts in decision block 1605. If the mobile stationdoes not have data to transmit, the process stops. Data may arrive fortransmission in a future iteration. If data is present, i.e. in the databuffer, proceed to step 1610 and/or 1615.

[0193] Steps 1610 and 1615 may be carried out simultaneously, orsequentially without respect to order. The functions of monitoring theHARQ channel and grant channels may be interrelated, as depicted in thisembodiment, or may be separable. This embodiment illustrates thefeatures of each. Those of skill in the art will readily adopt theprinciples disclosed herein to myriad alternate embodiments comprisingthe steps shown or subsets thereof.

[0194] In step 1610, the F-CACKCH is monitored for any HARQ commandsdirected to the mobile station based on a previous transmission. Asdescribed above, in this example, a mobile station may receive an ACK,NAK, or ACK-and-Continue (if the previous transmission was in responseto a grant). The grant channels assigned to the mobile station formonitoring, which may be a subset of the total number of grant channels,both individual and/or common, are monitored in step 1615 when aprevious request from the mobile station has been issued. Naturally, themobile station need not monitor either the F-CACKCH or the grantchannels if neither a prior transmission or prior request was made,respectively.

[0195] In decision block 1620, the HARQ portion of the process begins.If there was no previous transmission, the mobile station will notexpect any response on the F-CACKCH, and so the process may skip todecision block 1640 (details omitted for clarity). If anACK-and-Continue command is received in response to a previoustransmission (and a previous grant), proceed to step 1665. The mobilestation is granted an extended access based on the previous grant, andmay use the previously granted T/P. Note that, in alternate embodiments,a change in the common grant may or may not be applicable to change theprevious grant T/P, as described above. If an ACK-and-Continue is notreceived, proceed to decision block 1625.

[0196] In decision block 1625, if an ACK is received, a previous grant,if any, is not extended. Neither is retransmission required. The mobilestation may yet transmit autonomously, as will be apparent in the restof the flowchart. In the example embodiment, the remainder of theflowchart dealing with determining if a new grant is issued will not beapplicable, as the mobile station will not have an outstanding request(since doing so would use up capacity that the ACK-and-Continue featurewas deployed to prevent). However, in alternate embodiments, multiplerequests may be allowed to be simultaneously outstanding, perhaps toallow for requests to multiple ARQ channels. These alternates fallwithin the scope of the present invention, but the details are not shownfor the sake of clarity. If an ACK is received, proceed to decisionblock 1640. Note that decision block 1625 may include a test as towhether a previous transmission was made, and, if not, no ACK (orACK-and-Continue) would be expected, proceed to decision block 1640.

[0197] In decision block 1625, if an ACK is not received, then a NAK isassumed by default. Proceed to decision block 1630. In decision block1630, if the maximum number of subpackets has been transmitted, noretransmission is allowed. Proceed to decision block 1640 to test forany incoming grants, or to autonomously transmit, as will be describedbelow. If subpackets remain, proceed to step 1635 and retransmitaccording to the previous transmission, whether autonomous or scheduled.Then the process may stop for the current frame.

[0198] Decision blocks 1640 and 1645 are applicable when a previousrequest has been made, and a grant of one type or another may bereceived. If no previous request has been made, the mobile station mayproceed directly to decision block 1650 (details omitted for clarity).Note that, in this case, the mobile station needn't have performed step1615 either. Alternatively, decision blocks 1640 and 1645 may include inthe test whether or not a previous request was made, and ignore anindividual grant (most likely erroneously decoded) or a common grant(which would not be valid for a non-requesting mobile station).

[0199] In decision block 1640, if an individual grant is received inresponse to a previous request, proceed to step 1670. The mobile stationis granted a T/P as specified in the individual grant. If not, proceedto decision block 1645.

[0200] In decision block 1645, if a common grant is received in responseto a previous request, proceed to step 1675. The mobile station isgranted a T/P as specified in the common grant. If not, proceed todecision block 1650.

[0201] In decision block 1650, the mobile station determines whether ornot it wishes to make a request. Various factors, detailed above, may beincluded in the decision. For example, there may be a minimum amount ofdata required to make a request worthwhile. The amount of data awaitingtransmission should exceed that which can be transmitted autonomously.Further, if subsequent autonomous transmissions would exhaust the datafaster than waiting for a request and grant, then a request need not bemade. Quality of service may be incorporated in the decision. The mobilestation may determine a request is in order for certain types of data,but that autonomous transmission is suitable for others. Or, the mobilestation may be limited in its ability to make requests based on the QoSlevel of the mobile station. Various other examples are detailed above,and others will be apparent to those of skill in the art. Note that thedecision to transmit a request can be done for data buffers withdifferent QoS levels or groups of such data buffers to tailor thequality and delay provided to these data buffers. If a request isdesired, proceed to decision block 1655. If not, proceed to step 1680.The mobile station (unless otherwise limited) may make an autonomoustransmission, using the T/P specified as the maximum autonomous T/P.

[0202] In decision block 1655, if a previous request has been made, anyre-request conditions must be satisfied (examples detailed above withrespect to FIG. 13). The previous request may have been missed, orintentionally not granted based on the base station's allocationprocess. Or, a previous request may have been individually or commonlygranted, and then terminated with an ACK (or failed to be extended withan ACK-and-Continue). In any case, if the re-request conditionsapplicable are not satisfied, proceed to step 1680 to use the autonomousT/P, as just described. If the re-request conditions are satisfied,proceed to step 1660 and transmit the request. In the exampleembodiment, the request includes the amount of data in the buffer, andthe supportable T/P by the mobile station (which may vary over time). Agrant made in response to the request, if any, will come in a laterframe, and hence a subsequent iteration of this process 1600. In theexample embodiment, the mobile station may immediately make anautonomous transmission, and so proceed to step 1680, as just described.

[0203] Steps 1665-1680 each assign a T/P for the mobile station to usewhile transmitting. From any of those steps, proceed to step 1685. Instep 1685, the mobile station selects transmission parameters based onthe assigned T/P. Note that T/P is used as an example only. Other systemallocation parameters may be deployed in alternate embodiments. Forexample, other power values may be used that allow the mobile station toselect transmission parameters. Alternatively, less flexibility may beafforded to the mobile station, and one or more of the transmissionparameters may be specifically assigned (whether in a grant, or signaledfor use in autonomous transmission). Various methods for selectingtransmission parameters are known in the art. Other novel methods havebeen described above. FIG. 17, detailed below, details an example methodfor performing step 1685, as well as alternatives. Once the transmissionparameters have been selected, proceed to step 1690.

[0204] In step 1690, the mobile station transmits an amount of datacompatible with and in accordance with the selected parameters. Theparameters may include encoder packet size, modulation format, powerlevel for traffic and/or pilots (including primary, secondary, oradditional pilots), and any other transmission parameters known in theart. In the example embodiment, for an individual grant, a subpacket istransmitted on an ARQ channel. If a long grant flag is deployed, andincluded in the individual grant, the mobile station may transmit onmore than one ARQ channel. In the example embodiment, a common grant isvalid for 20 ms, or 4 ARQ channels. A commonly granted mobile stationmay use all of them. This method is suitable for use with multiplesubpackets and ARQ channels, as detailed herein, although the detailsare omitted in FIG. 16. These are examples only, and those of skill inthe art will readily extend these principles to myriad embodimentconfigurations. After transmission, the process then stops for thecurrent frame.

[0205]FIG. 17 is a flowchart illustrating a method of selectingtransmission parameters in response to an available T/P. It is suitablefor use in step 1685, detailed above, as well as any other embodiment inwhich transmission parameters are selected based on T/P. The processbegins in decision block 1710. A T/P is assigned for the mobilestation's use. If the mobile station's available transmit power isinsufficient to utilize the T/P assigned, proceed to step 1720 to reducethe T/P to accommodate the available transmit power.

[0206] In the example embodiment, a T/P is assigned. The P parameter isassociated with the pilot power, which is power-controlled by the basestation. Depending on the rate and format selected, additional pilotpower may be needed. In this example, additional pilot power istransmitted on a secondary pilot channel, the R-RICH in this case. Themobile station may want to include a margin, since the future directionof the power control commands are unknown, and may require additionalpilot power. The mobile station determines its available transmit powerand compares it with the sum of the pilot power (primary and secondary),traffic power, and any margin that is appropriate, to determine if theT/P granted (or assigned to autonomous transmission) can be supported.The T/P, modified as necessary, will be used to select transmissionparameters. Proceed to decision block 1730.

[0207] Decision block 1730 is an example of the flexibility that may beafforded to a mobile station. A single decision is used in this examplefor clarity, although additional levels may be introduced, as will beapparent to those of skill in the art. In this case, a decision is madewhether maximum throughput or low latency is desired. If low latency isdesired, proceed to step 1750. If maximum throughput is desired, proceedto step 1740.

[0208] In either case, a set of available parameters is defined. In thisexample, the parameters detailed in Table 1 are used. Myriadcombinations of parameters may be deployed. The system may updateparameters as desired through signaling. QoS may be factored in to limitthe choices a mobile has to a subset of the total set of parametercombinations. For example, an economy mobile station or data type mayhave a maximum T/P, regardless of the granted T/P (the scheduling basestation may also limit the grant as such). Or an economy mobile stationmay be forced to always select maximum throughput. In some cases,additional flexibility loosens the tight control the scheduling basestation has on the reverse link channel. By limiting the flexibility,additional capacity may be achieved. Thus, limiting flexibility toeconomy mobile stations or data types may be appropriate.

[0209] In step 1740, the mobile station desires maximum throughput, andso selects the maximum encoder size allowed by the T/P, assuming themaximum number of subpackets, and the expectation that all subpacketswill need to be transmitted, on average. In Table 1, this corresponds tolimiting the rows to those designated as having four 5 ms slots. Thereis one such row for each encoder packet size. The encoder packet size isthen selected, indexed by the T/P value. The remainder of theparameters, such as repetition factor, modulation format, Walsh channelselection, code rate, and so forth, are given in the appropriate row.Those of skill in the art will readily extend this to myriad sets ofchannel parameters, in addition to those shown in Table 1.

[0210] In step 1750, lower latency is desired, so fewer than the maximumnumber of subpackets are selected for the expected number of subpacketretransmissions (the actual number of retransmissions will vary,depending on the channel conditions, probability of error, etc.). Forthe lowest latency possible, the mobile station may select a row suchthat the expectation (to within a desired probability) is of successfultransmission in a single subpacket. Of course, if the data to betransmitted does not fit in a single subpacket, given the available T/P,actual latency may be reduced by selecting a row with more than onesubpacket (i.e. 2 or 3). Note that the base station may be able toreallocate subpackets not used by the mobile station (i.e. a decision ismade to use fewer than the maximum). In the example embodiment, the T/Pgrant is made assuming the mobile station has the right to use all thesubpackets. If an earlier subpacket is received correctly, the basestation may ACK-and-Continue (if additional data is awaitingtransmission), or reallocate the subsequent ARQ channel slots to adifferent mobile station. Again, too much latitude afforded to themobile station may result in less tight control over the RoT, and thuspotential throughput losses. Those of skill in the art will fine tunethe flexibility for the desired system performance.

[0211] Various methods for selecting the row from a table of possiblecombinations will be apparent to those of skill in the art, in light ofthe teachings herein. One example is to order the table based on therequired T/P for each combination of data rate (and other parameters)and expected number of subpackets. The mobile station would then choosethe combination with the features desired (latency, throughput, etc.)from the subset supportable by the given T/P. Or, more simply, the T/Pmay be an index to a specific row. The indexed row may be updatedthrough signaling. If additional flexibility is desired, the number ofsubpackets chosen may be indexed for the given T/P. Certain data types,such as FTP, for example, may always select the maximum throughputoption (i.e. maximum encoder packet size with largest expected number ofsubpacket retransmissions).

[0212] Again, this example is described using the example T/P systemallocation parameter. Alternate embodiments may use an alternateparameter, or may specifically direct one or more of the parameters foruse by the mobile station. From either step 1740 or 1750, once theparameters have been selected, the process may stop.

[0213] It should be noted that in all the embodiments described above,method steps can be interchanged without departing from the scope of theinvention. The descriptions disclosed herein have in many cases referredto signals, parameters, and procedures associated with the 1xEV-DVstandard, but the scope of the present invention is not limited as such.Those of skill in the art will readily apply the principles herein tovarious other communication systems. These and other modifications willbe apparent to those of ordinary skill in the art.

[0214] Those of skill in the art will understand that information andsignals may be represented using any of a variety of differenttechnologies and techniques. For example, data, instructions, commands,information, signals, bits, symbols, and chips that may be referencedthroughout the above description may be represented by voltages,currents, electromagnetic waves, magnetic fields or particles, opticalfields or particles, or any combination thereof.

[0215] Those of skill will further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

[0216] The various illustrative logical blocks, modules, and circuitsdescribed in connection with the embodiments disclosed herein may beimplemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

[0217] The steps of a method or algorithm described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in a software module executed by a processor, or in a combination of thetwo. A software module may reside in RAM memory, flash memory, ROMmemory, EPROM memory, EEPROM memory, registers, hard disk, a removabledisk, a CD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

[0218] The previous description of the disclosed embodiments is providedto enable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A wireless communication system, operable with aplurality of remote stations capable of transmission on a sharedresource, comprising: a receiver for receiving a plurality of accessrequests for transmission on the shared resource from a respectiveplurality of remote stations; a scheduler for allocating a portion ofthe shared resource to zero or more of the requesting remote stations inresponse to the plurality of access requests, the allocation comprisingzero or more individual access grants to zero or more requesting remotestations and zero or one common access grant to the remaining requestingremote stations; and a transmitter for transmitting the individualaccess grants to the respective remote stations on one or moreindividual grant channels and for transmitting the common access grantto the remaining remote stations on one or more common grant channels.2. The apparatus of claim 1, further operable with the plurality ofremote stations equipped to transmit autonomously on the sharedresource, using a limited portion of the shared resource, without anaccess request or access grant, and wherein the scheduler computes theexpected amount of the shared resource to be consumed by the autonomoustransmissions and allocates the portion of the shared resource forindividual and common access grants in response thereto.
 3. Theapparatus of claim 1, wherein an individual grant may allocate a portionof the shared resource that is greater than, less than, or equal to anyother individual or common grant.
 4. The apparatus of claim 1, whereinthe grant comprises a maximum traffic to pilot ratio (T/P).
 5. Theapparatus of claim 1, wherein the grant comprises a transmission rate.6. The apparatus of claim 1, wherein the grant comprises a transmissionpower level.
 7. The apparatus of claim 1, wherein the grant comprises amodulation format.
 8. The apparatus of claim 1, wherein the individualgrants are allocated to relatively higher geometry remote stations. 9.The apparatus of claim 1, wherein the scheduler determines theallocation in response to one or more Quality of Service (QoS) levels.10. The apparatus of claim 1, wherein the individual grants are validfor a first time duration and the common grant is valid for a secondtime duration, the second time duration greater than the first timeduration.
 11. The apparatus of claim 1, wherein the individual grantscomprise a duration flag, the duration flag indicating the individualgrant is for a first time duration or one or more additional timedurations, and one or more of the one or more additional time durationsare longer than the first time duration.
 12. The apparatus of claim 11,wherein the common grant is for a second time duration, the second timeduration longer than the first time duration.
 13. The apparatus of claim1, wherein an individual grant command is transmitted for a first timeduration and a common grant command is transmitted for a second timeduration, the second time duration longer than the first time duration.14. The apparatus of claim 1, further operable with one or more remotestations transmitting with permission from one or more access grants,the apparatus further comprising: a decoder for decoding one or morereceived packets and determining if the one or more received packetsdecoded without error; and wherein: the receiver further receives theone or more packets of data from one or more remote stations,respectively; the transmitter further transmits to the one or moreremote stations an acknowledgment and grant extension (ACK-and-Continue)command, respectively, when the respective received packet decodedwithout error and the access grant for the respective remote station isto be extended; and the scheduler determines the allocation of theportion of the shared resource in accordance with individual and commongrants extended with the one or more ACK-and-Continue commands.
 15. Abase station, operable with a remote station transmitting withpermission from an access grant, comprising: a receiver for receiving apacket of data from the remote station; a decoder for decoding thereceived packet and determining if the received packet decoded withouterror; and a transmitter for transmitting to the remote station anegative acknowledgment (NAK) command when the received packet did notdecode without error, an acknowledgment and grant extension(ACK-and-Continue) command when the received packet decoded withouterror and the access grant for the remote station is to be extended, andan acknowledgment (ACK) when the received packet decoded without errorand the access grant is not to be extended.
 16. The apparatus of claim15, wherein an ACK is transmitted with a first value, anACK-and-Continue is transmitted with a second value, and a NAK is nottransmitted.
 17. The apparatus of claim 16, wherein the first and secondvalues are of opposite polarity.
 18. A remote station, comprising: adata buffer for receiving data for transmission; a message generator forgenerating an access request message when the data buffer contains datafor transmission; a receiver for receiving one or more individual grantchannels and one or more common grant channels from a base station; amessage decoder for decoding an access grant directed to the remotestation, the access grant comprising an individual grant directed on oneof the one or more individual grant channels or a common grant on one ofthe one or more common grant channels; and a transmitter fortransmitting the access request message and for transmitting a portionof data from the data buffer in response to a decoded access grant. 19.The remote station of claim 18, wherein the transmitter furthertransmits a limited portion of the data in the data buffer autonomously,irrespective of whether an access grant has been received.
 20. Theremote station of claim 18, wherein the transmitter transmits on one ofa plurality of channels subsequent to a received grant.
 21. The remotestation of claim 18, wherein the transmitter transmits on two or more ofa plurality of channels subsequent to a received grant.
 22. The remotestation of claim 21, wherein the received grant is an individual grant,comprising a long grant flag, the long grant flag asserted.
 23. Theremote station of claim 21, wherein the received grant is a commongrant.
 24. The remote station of claim 18, wherein a grant comprises aT/P value.
 25. The remote station of claim 24, further comprising aprocessor for selecting transmission parameters based on a T/P value.26. The remote station of claim 25, wherein the transmission parameterscomprise an encoder packet size.
 27. The remote station of claim 25,wherein the transmission parameters comprise an expected number ofsubpacket transmissions.
 28. The remote station of claim 27, wherein thenumber of expected subpacket transmissions selected is the maximumnumber of subpacket transmissions.
 29. The remote station of claim 27,wherein the number of expected subpacket transmissions selected is lessthan the maximum number of subpacket transmissions.
 30. The remotestation of claim 25, wherein the transmission parameters comprise amodulation format.
 31. The remote station of claim 25, wherein thetransmission parameters comprise a transmit power level for a secondarypilot channel.
 32. The remote station of claim 25, wherein the processorreduces the T/P when the transmitter has insufficient transmit power totransmit according to the unreduced T/P.
 33. The remote station of claim18, wherein: the receiver further receives an ACK-and-Continue command;and the transmitter transmits an additional portion of data from thedata buffer in response to a previously decoded access grant.
 34. Theremote station of claim 18, wherein: the receiver further receives anACK command; and the transmitter ceases transmitting data from the databuffer in response to a previously decoded access grant.
 35. The remotestation of claim 34, wherein the transmitter further transmits a limitedportion of the data in the data buffer autonomously, subsequent to areceived ACK.
 36. The remote station of claim 18, wherein: the receiverfurther receives a NAK command; and the transmitter retransmits theportion of data from the data buffer previously transmitted in responseto a previously decoded access grant.
 37. The remote station of claim18, wherein the message generator generates an access request messageconditioned on the amount of data in the data buffer exceeding apre-determined threshold.
 38. The remote station of claim 18, whereinthe message generator generates an access request message conditioned ona Quality of Service (QoS) service level.
 39. The remote station ofclaim 18, wherein the message generator generates an access requestmessage conditioned on re-request conditions being satisfied withrespect to a previously generated access request message.
 40. The remotestation of claim 18, wherein the message generator generates an accessrequest message conditioned on desired data transmission latency. 41.The remote station of claim 18, wherein the message generator generatesan access request message conditioned on desired data transmissionthroughput.
 42. A remote station, comprising: a message encoder forencoding an access request message, the access request messagecomprising at least one of an indicator of an amount of data fortransmission, a supportable T/P, or a QoS indicator.
 43. An accessmessage, comprising at least one of an indicator of an amount of datafor transmission, a supportable T/P, or a QoS indicator.
 44. A basestation, comprising: a message encoder for encoding a grant message, thegrant message comprising at least one of a remote station identifier, agranted T/P, a long grant flag, or a QoS indicator.
 45. A grant message,comprising at least one of a remote station identifier, a granted T/P, along grant flag, or a QoS indicator.
 46. A wireless communicationsystem, comprising: a plurality of remote stations, each of a subset ofwhich transmit an access request message to form a plurality of accessrequest messages; a base station for: receiving the plurality of accessrequest messages; allocating a shared system resource among theplurality of remote stations; and transmitting zero or more individualaccess grants to a subset of the requesting remote stations and zero ormore common access grants to the remaining requesting remote stations.47. The wireless communication system of claim 46, wherein therequesting remote stations receive the transmitted individual or commonaccess grants and transmit data to the base station respectively inaccordance therewith.
 48. The wireless communication system of claim 47,wherein the base station: receives the transmitted data from theplurality of remote stations; decodes the received data to determine ifeach transmission from the plurality of remote stations was received inerror; and transmits an ACK-and-Continue command to a first subset ofthe plurality of remote stations to indicate that the data was receivedwithout error and to extend the previously granted common or individualgrants made to the first subset of the plurality of remote stations. 49.The wireless communication system of claim 48, wherein the base stationtransmits an ACK command to a second subset of the plurality of remotestations to indicate that the data was received without error and toterminate the previously granted common or individual grants made to thesecond subset of the plurality of remote stations.
 50. The wirelesscommunication system of claim 46, wherein a second subset of theplurality of remote stations transmit data autonomously.
 51. A method ofaccess control of a shared resource, comprising: receiving a pluralityof access requests for transmission on the shared resource from arespective plurality of remote stations; allocating a portion of theshared resource to zero or more of the requesting remote stations inresponse to the plurality of access requests, the allocation comprisingzero or more individual access grants to zero or more requesting remotestations and zero or one common access grant to the remaining requestingremote stations; transmitting the individual access grants to therespective remote stations on one or more individual grant channels; andtransmitting the common access grant to the remaining remote stations onone or more common grant channels.
 52. The method of claim 51, operablewith the plurality of remote stations equipped to transmit autonomouslyon the shared resource, using a limited portion of the shared resource,without an access request or access grant, further comprising: computingthe expected amount of the shared resource to be consumed by theautonomous transmissions and allocating the portion of the sharedresource for individual and common access grants in response thereto.53. The method of claim 51, wherein the allocation is performed inresponse to one or more Quality of Service (QoS) levels.
 54. The methodof claim 51, operable with one or more remote stations transmitting withpermission from one or more access grants, further comprising: decodingone or more received packets; determining if the one or more receivedpackets decoded without error; transmitting to the one or more remotestations an acknowledgment and grant extension (ACK-and-Continue)command, respectively, when the respective received packet decodedwithout error and the access grant for the respective remote station isto be extended; and wherein the allocation of the portion of the sharedresource is performed in accordance with individual and common grantsextended with the one or more ACK-and-Continue commands.
 55. A method ofaccess control of a shared resource, comprising, operable with a remotestation transmitting with permission from an access grant, comprising:receiving a packet of data from the remote station; decoding thereceived packet; determining if the received packet decoded withouterror; and transmitting to the remote station a negative acknowledgment(NAK) command when the received packet did not decode without error, anacknowledgment and grant extension (ACK-and-Continue) command when thereceived packet decoded without error and the access grant for theremote station is to be extended, and an acknowledgment (ACK) when thereceived packet decoded without error and the access grant is not to beextended.
 56. The method of claim 55, wherein an ACK is transmitted witha first value, an ACK-and-Continue is transmitted with a second value,and a NAK is not transmitted.
 57. The method of claim 56, wherein thefirst and second values are of opposite polarity.
 58. A method oftransmission, comprising: receiving data for transmission; storing thedata in a data buffer; generating an access request message;transmitting the access request message; receiving one or moreindividual grant channels and one or more common grant channels from abase station; decoding an access grant comprising an individual grantdirected on one of the one or more individual grant channels or a commongrant on one of the one or more common grant channels; and transmittinga portion of data from the data buffer in response to a decoded accessgrant.
 59. The method of claim 58, further comprising transmitting alimited portion of the data in the data buffer autonomously,irrespective of whether an access grant has been received.
 60. Themethod of claim 58, wherein a grant comprises a T/P value.
 61. Themethod of claim 60, further comprising selecting transmission parametersbased on the T/P value.
 62. The method of claim 61, wherein thetransmission parameters comprise an encoder packet size.
 63. The methodof claim 61, wherein the transmission parameters comprise an expectednumber of subpacket transmissions.
 64. The method of claim 61, whereinthe selecting comprises selecting the maximum number of subpackettransmissions.
 65. The method of claim 61, wherein the selectingcomprises selecting less than the maximum number of subpackettransmissions.
 66. The method of claim 60, further comprising reducingthe T/P when insufficient transmit power is available to transmitaccording to the unreduced T/P.
 67. The method of claim 58, furthercomprising: receiving an ACK-and-Continue command; and transmitting anadditional portion of data from the data buffer in response to apreviously decoded access grant.
 68. The method of claim 58, furthercomprising: receiving an ACK command; and ceasing transmitting data fromthe data buffer in response to a previously decoded access grant. 69.The method of claim 68, further comprising transmitting a limitedportion of the data in the data buffer autonomously, subsequent to areceived ACK.
 70. The method of claim 58, further comprising: receivinga NAK command; and retransmitting the portion of data from the databuffer previously transmitted in response to a previously decoded accessgrant.
 71. An apparatus, comprising: means for receiving a plurality ofaccess requests for transmission on the shared resource from arespective plurality of remote stations; means for allocating a portionof the shared resource to zero or more of the requesting remote stationsin response to the plurality of access requests, the allocationcomprising zero or more individual access grants to zero or morerequesting remote stations and zero or one common access grant to theremaining requesting remote stations; means for transmitting theindividual access grants to the respective remote stations on one ormore individual grant channels; and means for transmitting the commonaccess grant to the remaining remote stations on one or more commongrant channels.
 72. The apparatus of claim 71, operable with theplurality of remote stations equipped to transmit autonomously on theshared resource, using a limited portion of the shared resource, withoutan access request or access grant, further comprising: means forcomputing the expected amount of the shared resource to be consumed bythe autonomous transmissions and allocating the portion of the sharedresource for individual and common access grants in response thereto.73. An apparatus, operable with a remote station transmitting withpermission from an access grant, comprising: means for receiving apacket of data from the remote station; means for decoding the receivedpacket; means for determining if the received packet decoded withouterror; and means for transmitting to the remote station a negativeacknowledgment (NAK) command when the received packet did not decodewithout error, an acknowledgment and grant extension (ACK-and-Continue)command when the received packet decoded without error and the accessgrant for the remote station is to be extended, and an acknowledgment(ACK) when the received packet decoded without error and the accessgrant is not to be extended.
 74. An apparatus, comprising: means forreceiving data for transmission; means for storing the data in a databuffer; means for generating an access request message; means fortransmitting the access request message; means for receiving one or moreindividual grant channels and one or more common grant channels from abase station; means for decoding an access grant comprising anindividual grant directed on one of the one or more individual grantchannels or a common grant on one of the one or more common grantchannels; and means for transmitting a portion of data from the databuffer in response to a decoded access grant.
 75. The apparatus of claim74, further comprising means for transmitting a limited portion of thedata in the data buffer autonomously, irrespective of whether an accessgrant has been received.
 76. A wireless communication system,comprising: means for receiving a plurality of access requests fortransmission on the shared resource from a respective plurality ofremote stations; means for allocating a portion of the shared resourceto zero or more of the requesting remote stations in response to theplurality of access requests, the allocation comprising zero or moreindividual access grants to zero or more requesting remote stations andzero or one common access grant to the remaining requesting remotestations; means for transmitting the individual access grants to therespective remote stations on one or more individual grant channels; andmeans for transmitting the common access grant to the remaining remotestations on one or more common grant channels.
 77. The wirelesscommunication system of claim 76, operable with the plurality of remotestations equipped to transmit autonomously on the shared resource, usinga limited portion of the shared resource, without an access request oraccess grant, further comprising: means for computing the expectedamount of the shared resource to be consumed by the autonomoustransmissions and allocating the portion of the shared resource forindividual and common access grants in response thereto.
 78. A wirelesscommunication system, operable with a remote station transmitting withpermission from an access grant, comprising: means for receiving apacket of data from the remote station; means for decoding the receivedpacket; means for determining if the received packet decoded withouterror; and means for transmitting to the remote station a negativeacknowledgment (NAK) command when the received packet did not decodewithout error, an acknowledgment and grant extension (ACK-and-Continue)command when the received packet decoded without error and the accessgrant for the remote station is to be extended, and an acknowledgment(ACK) when the received packet decoded without error and the accessgrant is not to be extended.
 79. A wireless communication system,comprising: means for receiving data for transmission; means for storingthe data in a data buffer; means for generating an access requestmessage; means for transmitting the access request message; means forreceiving one or more individual grant channels and one or more commongrant channels from a base station; means for decoding an access grantcomprising an individual grant directed on one of the one or moreindividual grant channels or a common grant on one of the one or morecommon grant channels; and means for transmitting a portion of data fromthe data buffer in response to a decoded access grant.
 80. The wirelesscommunication system of claim 79, further comprising means fortransmitting a limited portion of the data in the data bufferautonomously, irrespective of whether an access grant has been received.81. Processor readable media operable to perform the following steps:receiving a plurality of access requests for transmission on the sharedresource from a respective plurality of remote stations; allocating aportion of the shared resource to zero or more of the requesting remotestations in response to the plurality of access requests, the allocationcomprising zero or more individual access grants to zero or morerequesting remote stations and zero or one common access grant to theremaining requesting remote stations; transmitting the individual accessgrants to the respective remote stations on one or more individual grantchannels; and transmitting the common access grant to the remainingremote stations on one or more common grant channels.
 82. The media ofclaim 81, operable with the plurality of remote stations equipped totransmit autonomously on the shared resource, using a limited portion ofthe shared resource, without an access request or access grant, furtheroperable to perform: computing the expected amount of the sharedresource to be consumed by the autonomous transmissions and allocatingthe portion of the shared resource for individual and common accessgrants in response thereto.
 83. Processor readable media operable with aremote station transmitting with permission from an access grant andoperable to perform the following steps: receiving a packet of data fromthe remote station; decoding the received packet; determining if thereceived packet decoded without error; and transmitting to the remotestation a negative acknowledgment (NAK) command when the received packetdid not decode without error, an acknowledgment and grant extension(ACK-and-Continue) command when the received packet decoded withouterror and the access grant for the remote station is to be extended, andan acknowledgment (ACK) when the received packet decoded without errorand the access grant is not to be extended.
 84. Processor readable mediaoperable to perform the following steps: receiving data fortransmission; storing the data in a data buffer; generating an accessrequest message; transmitting the access request message; receiving oneor more individual grant channels and one or more common grant channelsfrom a base station; decoding an access grant comprising an individualgrant directed on one of the one or more individual grant channels or acommon grant on one of the one or more common grant channels; andtransmitting a portion of data from the data buffer in response to adecoded access grant.
 85. The media of claim 84, further operable toperform transmitting a limited portion of the data in the data bufferautonomously, irrespective of whether an access grant has been received.